021299   Sanjiva Kumar;Debnath A;Tokas R B;Divakar Rao K;Udupa D V;Sahoo N K (Applied Spectroscopy Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: sanjivk@barc.gov.in) : Optimization for sinusoidal profiles in surface relief gratings recorded on photoresist. Pramana J Phys 2014, 82(2), 289-94.

The formations of sinusoidal surface relief structures recorded in positive photoresist (Allresist AR-P 3120) have been studied and optimized for different recording parameters of gratings with spatial frequency of <126> 1200 grooves/mm. A stable sinusoidal pattern generated using a two-beam laser interferometric technique was recorded in thin films of positive photoresist deposited on glass substrates. Several gratings were generated by varying the exposure time of interference pattern and time of chemical development of exposed media. Time duration of exposure for 90 s and chemical development for 15 s were observed to be optimum for the translation of the sinusoidal interference pattern into nearly-sinusoidal profiled grooves in the gratings for a developer AR-300-26 of dilution of 2:1 (developer:de-ionized water).

4 illus, 11 ref

021298   Sahoo A C;Shah M L;Mandal P K;Pulhani A K; Gupta G P;Dev V;Suri B M (Laser & Plasma Technology Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: mlshah@barc.gov.in) : Measurement of radiative lifetime in atomic samarium using simultaneous detection of laser-induced fluorescence and photoionization signals. Pramana J Phys 2014, 82(2), 403-8.

In this paper, we report the investigations of lifetime measurement of odd-parity energy level 19009.52 cm^-1 of Sm I using simultaneous detection of laser-induced fluorescence and laser-induced photoionization signals employing pump-probe technique. To the best of our knowledge, this is for the first time that the results obtained using laser-induced fluorescence and photoionization techniques have been compared with each other. The obtained results match well with those reported in the literature.

2 illus, 1 table, 6 ref

021297   Razdan A K;Veerabuthiran S;Jindal M K;Sharma R K (Lidar and Beam Diagnostics Div, Laser Science & Technology Centre, Delhi-110 054, Email: akraz61@rediffmail.com) : Infrared differential absorption lidar for stand-off detection of chemical agents. Pramana J Phys 2014, 82(2), 385-9.

A compact trolley-mounted pulsed transverse electric atmospheric pressure (TEA) carbon dioxide laser-based differential absorption lidar (DIAL) system capable of stand-off detection of chemical clouds in aerosol and vapour form upto about 200 m range in the atmosphere has been developed and assembled at Laser Science and Technology Centre (LASTEC), Delhi. The system was tested successfully with diethyl ether (DEE) (a toxic industrial chemical (TIC)) and differential absorption signals at λ_on (strong absorption, 9R16) and λ_off (weak absorption, 10R26) wavelengths were recorded for stand-off distances upto <126> 100 m (open air ground path). This paper discusses the technical details of trolley-mounted CO₂ DIAL system and the data generated during the test and evaluation of this sensor using DEE aerosols.

3 illus, 7 ref

021296   Rawat V S;Kawade N;Sridhar G;Singh S;Gantayet L M (Laser & Plasma Technology Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: vrawat@barc.gov.in) : Measurement of flow fluctuations in single longitudinal mode pulsed dye laser. Pramana J Phys 2014, 82(2), 203-10.

A simple technique had been demonstrated for measuring flow-induced fluctuations in the single longitudinal mode (SLM) pulsed dye laser. Two prominent frequency components of 10.74 Hz and 48.83 Hz were present in the output of the Nd:YAG-pumped SLM dye laser. The flow-induced frequency component of 48.83 Hz was present due to the revolution per minute of the motor attached to the magnetically coupled gear pump. The time average bandwidth of 180 MHz has been obtained for this SLM dye laser. The effect of pump pulse energy on the bandwidth of the SLM dye laser was studied. The bandwidth of the SLM dye laser was increased to 285 MHz from 180 MHz, when the pump pulse energy was increased to 0.75 mJ from 0.15 mJ for a constant dye flow velocity of 0.5 m/s.

7 illus, 7 ref

021295   Ram S P;Tiwari S K;Mishra S R;Rawat H S (Laser Physics Application Section, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: spram@rrcat.gov.in) : Optimization of transfer of laser-cooled atom cloud to a quadrupole magnetic trap. Pramana J Phys 2014, 82(2), 419-23.

The experimental results on transfer of laser-cooled atom cloud to a quadrupole magnetic trap. We show that by choosing appropriately the ratio of potential energy in magnetic trap to kinetic energy of cloud in molasses, we can obtain the maximum phase-space density in the magnetic trap. These, results guide us to choose the value of current to be switched in the quadrupole coils used for magnetic trapping for a given temperature of the cloud after molasses. This study is also useful to set the initial phase-space density of the cloud before evaporative cooling.

4 illus, 4 ref

021294   Rajesh C S;Anjana R;Sreeroop S S;Sudha Kartha C (Physics Dep, Cochin Science and Technology Univ, Cochin-682 022, Email: csk@cusat.ac.in) : Reflection mode holographic recording in methylene blue-sensitized polyvinyl alcohol acrylamide films. Pramana J Phys 2014, 82(2), 259-64.

Photopolymer systems can produce good image quality holograms that does not require any post-processing and are environmentally stable with good diffraction efficiency. The present work reports the development of a methylene blue-sensitized polyvinyl alcohol acrylamide (MBPVA/AA) photopolymer system for recording white light reflection holograms. Reflection gratings were recorded in the photopolymer films with different concentrations of methylene blue (MB). Various parameters affecting the holographic properties of the samples were also studied. The holographic performance of the material is found to depend on its chemical composition and the recording parameters.

6 illus, 9 ref

021293   Prasad D;Thakur A N;Jai Prakash (Basic Science Dep, U P Textile Technology Institute, 11/208, Suterganj, Kanpur, Uttar Pradesh-208 001) : Comparative study of mechanisms and analysis techniques involved in thermally stimulated depolarization and thermoluminescence processes. Ultra Scient phys Sci-Sect A 2013, 25(2), 297-306.

In the present work a comparative study have been done between two thermally stimulated processes, namely Thermally Stimulated Depolarization (TSD) and Thermoluminescence(TL). The depolarization current density or ionic thermocurrent density J depends on the rate of depolarization of IV dipoles and the occurrence TL glow curves are goverened by Adirovitch set of equations. The thermally stimulated spectrums of both the processes are of same nature. In this paper the similarities and counter quantities in both the processes have been discussed. It has also been found that the analysis technique, for determination of dielectric relaxation parameters, decay parameters and order of kinetics, are also similar for both processes.

11 ref

021292   Prakash O;Kumar J;Mahakud R;Kumbhkar U;Nakhe S V;Dixit S K (NO, Raja Ramanna Centre for Advanced Technology, R&D C-1 Block, Indore-452 013, Email: oprakash@rrcat.gov.in) : Development of tilted fibre bragg gratings using highly coherent 255 nm radiation. Pramana J Phys 2014, 82(2), 255-8.

This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission and reflection spectra of the tilted fibre Bragg gratings (TFBG) were studied for the tilt angles of 0° (normal FBG), 1°, 3° and 4° between the fibre axis and the interference fringe plane. It was observed that as the angle of fibre axis and phase mask increased, the main Bragg peak shifted towards the higher wavelength and transmission dip decreased. The transmission dip of the cladding mode first increased and then decreased after reaching a maximum with the increase in the tilt angle.

2 illus, 8 ref

021291   Pradhan S;Mishra S;Behera R;Kawade N;Das A K (Laser Plasma Technology Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: spradhan@barc.gov.in) : Spectral narrowing of coherent population trapping resonance in laser-cooled and room-temperature atomic gas. Pramana J Phys 2014, 82(2), 301-6.

Investigated coherent population trapping (CPT) in laser-cooled as well as room-temperature (with and without buffer gas) rubidium atoms. The characteristic broad signal profile emerging from the two-photon Raman resonance for room-temperature atomic vapour is consistent with the theoretical calculation incorporating associated thermal averaging. The spectral width of the dark resonance obtained with cold atoms is found to be broadened, compared to room-temperature vapour cell, due to the feeble role played by thermal averaging, although the cold atomic sample significantly overcomes the limitation of the transit time broadening. An alternative way to improve transit time is to use a buffer gas, with which we demonstrate that the coherent population trapping signal width is reduced to < 540 Hz.

4 illus, 6 ref

021290   Philip A;Thomas S;Rajeev Kumar K (Instrumentation Dep, Cochin University of Science and Technology, Cochin 682 022, Email: rajeev@cusat.ac.in) : Calculation of growth per cycle (GPC) of atomic layer deposited aluminium oxide nanolayers and dependenceof GPC on surface OH concentration. Pramana J Phys 2014, 82(3), 563-9.

A theoretical calculation is presented for the growth per cycle (GPC) of the film and the variation of GPC with OH concentration on the substrate surface. The calculated GPC range (0.179 nm-0.075 nm) agrees well with reported experimental values. The present approach yielded a density of 2.95 g/cc for the deposited films. The number of monolayers (ML) as a function of the OH concentration on the substrate surface is calculated and is found to be in the range of 58.4-24.2% of the total number of cycles of deposition. Effective monolayer thickness is calculated as 0.31 nm.

3 illus, 2 tables, 22 ref

021289   Parihar N;Mukherjee G K (Dr KSKGR Lab, Indian Institute of Geomagnetism, Allahabad-221 505, Email: navindeparihar@gmail.com) : Case study of gravity waves observed in OH rotational temperatures at Kolhapur (16.8 N, 74.1 E), India. Indian J Radio Space Phys 2014, 43(1), 67-74.

Ground-based measurements of OH (8, 3) Meinel band emissions were carried out at Kolhapur (16.8°N, 74.1°E), India during November 2002 - May 2003 using two tilting filter photometers. OH rotational temperature <126> a proxy of atmospheric temperature around 87 km, were derived from the intensity information of P₁(2) and P₁(4) lines of OH (8, 3) band. On most nights, strong well-defined oscillations having periodicities in the range of 1 - 3 h were observed in OH temperature series. In this paper, a case study of such short-period oscillations, observed on few nights in the OH temperature, has been presented.

6 illus, 1 table, 27 ref

021288   Pabira Nath;Hussain I;Biswas R (Applied Photonics and Nanophotonics Laboratory, Physics Dep, Tezpur Univ, Sonitpur-784 028, Email: pnath@tezu.ernet.in) : Liquid-level sensing based on periodic evanescent field absorption from a multimode optical fibre. Curr Sci 2014, 106(3), 424-7.

The working of a robust, long dynamic range, quasi-continuous fibre-optic liquid-level sensor is demonstrated in this communication. The sensor principle is based on periodic evanescent light wave absorption when rising level of liquid gradually replaces the surrounding air medium from a periodically uncladded step-index multimode optical fibre which would cause local variation in normalized frequency parameter (V) of the fibre. With our proposed sensor design, liquid-level variation as small as 2.5 cm can be measured with high accuracy and repeatability, which can be further enhanced by reducing the spacing between two adjacent regions of the fibre. Owing to its simplicity and robustness in operation, we envision that the proposed sensing technique could emerge as an alternative to the existing optical-based liquid-level sensors.

5 illus, 13 ref

021287   Nithyanandan K;Raja R V J;Uthayakumar T; Porsezian K (Physics Dep, Pondicherry Univ, Pondicherry-605 014, Email: nithi.physics@gmail.com) : Impact of higher-order dispersion in the modulational instability spectrum of a relaxing coupled saturable media. Pramana J Phys 2014, 82(2), 339-45.

A theoretical analysis of modulational instability (MI) of optical pulses propagating near the zero dispersion wavelength of a lossless fibre with the effect of delayed saturable nonlinear response is presented. We calculate the exact dispersion relation with the effect of higher dispersion for the harmonic perturbation. We analysed the impact of fourth-order dispersion effects in the MI spectrum. We examine the possibility of MI in both dispersion regimes, regardless of the sign of the group velocity dispersion.

3 illus, 4 ref

021286   Nakitare W M;Merenga A S (Physics Dep, Kenyatta University, P.O. Box, 43844 Nairobi, Kenya, Email: michacnakitare439@gmail.com) : Effect of inoculation on storage and loss moduli of high density polyethylene/cellulose blend. Int J appl Sci Engng Res 2014, 3(2), 464-72.

Plastic materials, particularly Polyethylene (PE) are the potential source of environmental pollution. In the present study, a fungal strain was isolated from the dumpsite capable of adhering to High density polyethylene (HDPE) and its cellulose (CELL) blends surface. The fungal strain was identified as Aspergillus niger. Dynamic mechanical analysis (DMA) was used to monitor the effect of Aspergillus niger on the HDPE/CELL blends. The viscoelastic behavior of HDPE/CELL blends was studied to give an insight on the dynamic mechanical properties such as storage modulus, loss modulus. The relaxation processes were greatly affected by inoculation. The intensity of both α and β peaks significantly reduced on inoculation due to the degradation of the blends by A.niger. The β-relaxation was heavily affected by inoculation suggesting that microbial attack started in the crystalline-amorphous interface. However, the crystalline part was also affected by the degradation process. Vogel-Fulcher-Tamman(VFT) model offered a better understanding of the time-temperature dependence of the mean relaxation frequency τ for the blends.

6 illus, 1 table, 14 ref

021285   Murthy M V N;Rajasekaran G (NO, The Institute of Mathematical Sciences, CIT Campus, Teramani PO, Chennai-600 113, Email: murthy@imsc.res.in) : Anomalous Kolar events revisited: Dark matter?. Pramana J Phys 2014, 82(3), 609-15.

The possibility of the unexplained Kolar events, recorded in the 1970s and 1980s, being due to the decays of dark matter particles of mass in the range of 5-10 GeV, is pointed out.

1 illus, 1 table, 16 ref

021284   Mondal S;Singh S P;Mukhopadhyay S;Date A; Hussain K;Mukherjee S;Datta P K (Physics Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: pkdatta.ittkgp@gmail.com) : Comparative study on dual colour soft aperture cascaded second-order mode-locking with different nonlinear optical crystals. Pramana J Phys 2014, 82(2), 313-9.

A comparative study in terms of optimized output power and stability is made on cascaded second-order nonlinear optical mode-locking with KTP, BBO and LBO crystals for both 1064 nm and 532 nm. Large nonlinear optical phase shift achieved in a non-phase-matched second harmonic generating crystal, is transformed into amplitude modulation through soft aperturing the nonlinear cavity mode variation at the laser gain medium to mode-lock a Nd:YVO₄ laser. The laser delivers stable dual wavelength cw mode-locked pulse train with pulse duration 10.3 ps and average power of 1.84 W and 255 mW at 1064 nm and 532 nm respectively for the optimum performance in type-Il KTP crystal. The exceptional stability achieved with KTP is accounted by simulating the mode-size variation with phase mismatch.

4 illus, 12 ref

021283   Mithun T;Porsezian K (Physics Dep, School of Physical, Chemical and Applied Sciences, Pondicherry Univ, Pondicherry-605 014, Email: mithunt1987@gmail.com) : Modulational instability of nematic phase. Pramana J Phys 2014, 82(2), 307-12.

Numerically observe the effect of homogeneous magnetic field on the modulation-ally stable case of polar phase in F = 2 spinor Bose-Einstein condensates (BECs). Also investigate the modulational instability of uniaxial and biaxial (BN) states of polar phase. Our observations show that the magnetic field triggers the modulational instability and demonstrate that irrespective of the magnetic field effect the uniaxial and biaxial nematic phases show modulational instability.

2 illus, 15 ref

021282   Mirza A B;Singh S (NO, School of Physics, Hyderabad Univ, Hyderabad-500 046, Email: suneelsp@uohyd.ernet.in) : Electromagnetically-induced transparency in doppler-broadened five-level systems. Pramana J Phys 2014, 82(2), 295-300.

Study electromagnetically-induced transparency (EIT) of a probe field in a Doppler-broadened five-level K-type atomic system driven by three strong laser (coupling) fields. Effect of wave-vector mismatch occurring when the coupling field frequency is higher than that of the probe field frequency (λ_c <60> λ_p) are considered. Under the influence of the coherent coupling fields, the steady-state linear susceptibility of the probe laser shows that the system can have single, double or triple EIT windows depending on the amplitude and detuning of the coupling fields.

3 illus, 7 ref

021281   Mathivanan V;Haris M;Prasanyaa T;Amgalan M (Physics Dep, Karunya University, Karunya Nagar, Coimbatore 641 114, Email: harismuthiah@gmail.com) : Synthesis and characterization of gel-grown cobalt tartrate crystals. Pramana J Phys 2014, 82(3), 537-48.

Crystals of cobalt tartrate are grown from the gel using chemical reaction method.The functional groups are found from Fourier transform infrared spectroscopy (FTIR). The OHstretching mode owing to water, carbonyl group, CH stretching modes and metal-oxygen stretchingare identified. The unit cell dimensions, interaxial angles and unit cell volume are found frompowder X-ray diffraction studies (XRD) which show the orthorhombic nature of the crystal. Themagnetic study is used to find the magnetic susceptibility and magnetic moment of the grown crystal.It reveals the magnetic nature of the crystal. Thermogravimetric analysis (TGA) and differentialscanning calorimetry (DSC) are done to find the thermal properties of the crystal which manifestthe water of hydration in the crystal. The variation of dielectric constant with respect to the applied frequency shows the polarization property of the crystal. The AC conductivity is increased proportionallywith increase in frequency. The reverse nature is found for the AC resistivity. The natureof the composition of the crystals affects the dielectric properties.

9 illus, 4 tables, 26 ref

021280   Malik A;Sendhil Raja S;Gupta P K (NO, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: asmitamalik@rrcat.gov.in) : Versatile laser microfabrication techniques for lab-on-chip devices in general and uranium analysis in particular. Pramana J Phys 2014, 82(2), 243-8.

In a plethora of microfabrication processes available now-a-days, one needs to choose the best possible option suitable for the job on-hand. This paper discusses three versatile approaches to fabricate microchips for lab-on-chip (LOC) applications in general and uranium analysis in water samples as a specific case. Laser-direct patterning succeeded by soft lithography, laser micropat-terning followed by HF etching and micromilling have been demonstrated which not only suit the objective of uranium detection but also for most of the LOC applications. The different techniques elaborated enable development of LOCs in polymers as well as glass with a depth ranging from few microns to 100 μm or higher while squeezing the reaction lengths of <126>10 cm on a 20 mm x 32 mm chip. This development equips one to design and develop more complicated LOC devices to take advantage of their hastened reaction cycle with minimal waste in terms of capital and maintenance cost.

5 illus, 2 ref

021279   Lokhande B J;Ambare R C;Mane R S;Bharadwaj S R (School of Physical Sciences, Solapur University, Solapur-413 255, Email: bjlokhande@yahoo.com) : Potential specific capacitance in layered Nickel Ferrite Electrochemical Supercapacitors. Invertis J renewable Energy 2013, 3(2), 67-73.

Nickel ferrite electrodes for electrochemical supercapacitors were made from a successive ionic layer adsorption and reaction (SILAR) chemical method. Their structural elucidation and morphological evolution studies were made and further investigated in electrochemical cyclic-voltamll1etry characteristic measurement. Face-centered cubic crystal structure of nickel ferrites composed of several irregular islands is confirmed. Brief flow chart is discussed for clear in-depth understanding of the formation nickel ferrite. Due to a significant reversible pseudocapacitive contribution 11lckel ferrite electrochemical supercapacitor contributes 555.5 Fig specific capacitance at 2 m V/s. Electrochemical impedance analysis measurement, along with an equivalent circuit details, is also provide for understanding the charge transport kinetics across various interfaces.

8 illus, 2 tables, 24 ref

021278   Linslal C L;Peter J;Mathew S;Kailasnath M (NO, International School of Photonics, Cochin Science & Technology Univ, Cochin-682 022, Email: linslal@gmail.com) : Multimode laser emission from dye-doped hollow polymer optical fibre. Pramana J Phys 2014, 82(2), 233-6.

Well-resolved multimode laser emission was observed for the first time from a freestanding microring cavity based on Rhodamine B dye-doped hollow polymer optical fibre by transverse pumping. Fibres with different diameters such as 180, 460, 640 and 800 μm were fabricated from a dye-doped hollow polymer preform. A blueshift in the mode structure was observed with decrease in fibre diameter leading to wide range tunability of the laser emission.

2 illus, 6 ref

021277   Lin H;Cai J (School of Mathematics and Statistics, Minnan Normal University, Zhangzhou, China 363000, Email: 839480327@qq.com) : Finite-time synchronization of a class of autonomous chaotic systems. Pramana J Phys 2014, 82(3), 489-98.

Some criteria for achieving the finite-time synchronization of a class of autonomouschaotic systems are derived by the finite-time stability theory and Gerschgorin disc theorem. Numerical simulations are shown to illustrate the effectiveness of the proposed method.

6 illus, 14 ref

021276   Kumar J;Mahakud R;Prakash O;Dixit S K (Laser System Engineering Section, Raja Ramanna Centre for Advanced Technology, R & D Block C-3, Indore-452 013, Email: jkmadaan@rrcat.gov.in ) : HF-based clad etching of fibre bragg grating and its utilization in concentration sensing of laser dye in dye-ethanol solution. Pramana J Phys 2014, 82(2), 265-9.

This paper presents a fiber Bragg grating (FBG) based sensor to study the concentration of laser dye in dye-ethanol solution. The FBG used in this experiment is indigenously developed using 255 nm UV radiations from copper vapour laser. The cladding of the FBG was partially removed using HF-based etching to make FBG sensitive to changes in the surrounding refractive index. The experimental results on the shift of the Bragg peak wavelength with HF etching and different dye concentration in ethanol are presented. The Bragg wavelength shifted from 1534.670 nm to 1534.225 nm in 30 min and from this point to 1533.97 in the next 2 min. The clad-etched Bragg peak shifted almost linearly from 1534.056 nm to 1534.162 nm as surrounding dye concentration in ethanol changes from 0 mM to 1.5 mM. It was observed that sensitivity depends on the concentration of the solution and found to be 70 pm/mM.

6 illus, 12 ref

021275   Khan S;Jayabalan J;Singh A;Chari R;Pal S; Porwal S;Sharma T K;Oak S M (Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: skhan@rrcat.gov.in) : Coherent oscillations of holes in GaAs_0.86P_0.14/Al_0.7Ga_0.3As surface quantum well. Pramana J Phys 2014, 82(2), 359-64.

We show that in a GaAs_0.86P_0.14/Al_0.7Ga_0.3 As near-surface quantum well, there is coherent oscillation of holes observed in time-resolved reflectivity signal when the top barrier of the quantum well is sufficiently thin. The quantum well states interact with the surface states under the influence of the surface electric field. The time period of the observed oscillation is 120 ± 10 fs.

6 illus, 12 ref

021274   Kapoor K;Anuj Kumar;Dass N (Physics Dep, College of Engineering Roorkee, Roorkee 247 667, Email: kmlsrk@rediffmail.com) : New temperature-dependent equation of state of solids. Pramana J Phys 2014, 82(3), 549-61.

A temperature-dependent equation of state (EOS) of solids is discussed which is found to be applicable in high-pressure and high-temperature range. Presentequation of state has been applied in 18 solids. The calculated data are found in very good agreementwith the data available from other sources.

5 illus, 2 tables, 29 ref

021273   Joshi M P;Raj Mohan S;Kolli B;Mishra S P; Palai A K;Kanai T;Dhami T S;Kukreja L M;Samui A B (Laser Materials Processing Div, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: mukesh@rrcat.gov.in) : Second harmonic generation from corona-poled polymer thin films of Y-shape chromophore with different isolation groups. Pramana J Phys 2014, 82(2), 283-8.

Characterize thermal stability of second harmonic generation (SHG) properties of four different Y-type polymers poled using corona poling method. These polymers are based on donor-acceptor-donor-type repeating unit with different aromatic moieties acting as donors and dicyanomethylene acting as an acceptor through conjugated bridge. The donor varies from different substituted benzene to phenothiazine. Polymer containing phenothiazine as donor showed higher SHG intensity and high temperature stability due to rigid repeating unit of phenothiazine compared to others with benzene in the main chain.

3 illus, 1 table, 6 ref

021272   Harshavardhan Reddy P;Sekhar H;Narayana Rao S (Laser Laboratory, School of Physics, Hyderabad Univ, Hyderabad-500 046, Email: dnr.laserlab@gmail.com) : Picosecond nonlinear optical properties of cuprous oxide with different nano-morphologies. Pramana J Phys 2014, 82(2), 321-5.

Cuprous oxide nanoclusters, microcubes and microparticles were successfully synthesized by a simple co-precipitation method. Phase purity and crystallinity of the samples were studied by using X-ray powder diffraction. Transmission electron microscopy (TEM) images show different morphologies like nanoclusters, microcubes and microparticles. For linear and nonlinear optical measurements, the as-synthesized Cu2O with different morphologies were dispersed in isopropanol solution. The absorption spectrum recorded in the visible regions shows peaks that depend on the morphology of the particles and the peak shifts towards red region as one goes from nanoclusters to microparticles. Simple open-aperture Z-scan technique is used to measure nonlinear optical properties of cuprous oxide at 532 nm, 30 ps excitation at 10 Hz repetition rate. Cuprous oxide nanoclusters show reverse saturable absorption (RSA) behaviour, the microcubes and microparticles at a similar concentration exhibit saturable absorption (SA) type of behaviour at lower peak intensities and exhibit RSA within SA at higher peak intensities. The results show that the transition from SA to RSA can be ascribed to the two-photon absorption (TPA) process.

4 illus, 11 ref

021271   Hamed A M (Physics Dep, Faculty of Science, Ain Shams University, Cairo 11566, Egypt, Email: amhamed73@hotmail.com) : Step index fibre using laser interferometer. Pramana J Phys 2014, 82(3), 529-36.

A model is suggested to describe the fringe shift which occurs due to the phase variationsof cladded glass fibre introduced between the two plates of the liquid wedge interferometerilluminated with a He-Ne laser. The fringe shift of the phase object which appears in the denominatorof the Airy distribution formula of the multiple beam interference is represented in the harmonicterm. An experiment is conducted using liquid wedge interferometer where the step index glassfibre of a nearly quadratic thickness variation is introduced between the two plates of the interferometer.The obtained fringe shift shows a good agreement with the proposed quadratic model. TheMatlab code is written to plot the interferometer fringes comprising the shift of the step index fibre.Secondly, recognition of elliptical fibres is outlined using tomographic imaging. Finally, results and concluding remarks are given.

6 illus, 20 ref

021270   Hamad S;Podagatlapalli G K;Tewari S P;Rao S V (NO, School of Physics, Hyderabad Univ, Hyderabad-500 046, Email: svrsp@uohyd.ernet.in) : Synthesis of Cu₂O, CuCl, and Cu₂OCl₂ nanoparticles by ultrafast laser ablation of copper in liquid media. Pramana J Phys 2014, 82(2), 331-7.

Copper complex nanoparticles were fabricated from bulk copper using picosecond laser ablation in water and chloroform. We found that composition of the nanoparticles was CuCl and Cu₂OCl₂ in chloroform at three different input fluences; Cu₂O in water which was confirmed from the data of EDAX, UV-Visible absorption spectra, and selected area electron diffraction pattern. We have also performed nonlinear optical studies of colloidal nanoparticles using Z-scan technique at 800 nm and <126>2 ps laser pulses. Cu₂O NPs exhibited two-photon absorption at lower peak intensities while three-photon absorption was observed at higher peak intensities. Other samples exhibited two-photon absorption at all peak intensities.

4 tables, 15 ref

021269   Gupta M;Jagtap K K;Sudarsan V;Ray A K (Laser & Plasma Technology Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: monikaatgupta@gmail.com) : Taming fluorescence yield of dye insensitive to temperature by non-covalent complex with the host CB[7] for aqueous dye lasers. Pramana J Phys 2014, 82(2), 277-81.

Quantum yield of fluorescence (QYF) of widely used Rhodamine (RhB) dye in ethanol and water was observed to decrease rapidly with increase in temperature of the dye solutions, which was correlated to enhanced torsional motion of its flexible diethylamino groups. This is harmful for its use in high-average power dye lasers, pumped by copper vapour laser (CVL) or diode-pumped solid-state green laser (DPSSGL), in which bulk temperature of the dye solution was found to increase due to the heat generated by circulation pumps and non-radiative decay processes of excited dye molecules. The QYF of RhB dye in water was found to be not sensitive to temperature in the practical operating region 16-25°C of dye laser by adopting supramolecular route to form an inclusion complex of RhB with the container molecule cucurbit[7]uril (CB[7]).

5 illus, 5 ref

021268   George J;Bindra K S;Oak S M (Solid State Laser Div, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: jogy@rrcat.gov.in) : LOPUT laser: a novel concept to realize single longitudinal mode laser. Pramana J Phys 2014, 82(2), 185-90.

Propose a novel type of cavity design to generate single longitudinal mode laser known as LOPUT cavity. LOPUT cavity stands for linear orthogonally polarized modes resulting in unidirectional travelling wave cavity. The technique can be applied to both isotropic as well as anisotropic gain mediums. In the present paper, we applied the technique to anisotropic gain medium such as a-cut Nd:YVO₄. Using the LOPUT cavity, we demonstrated nearly 2 W of single longitudinal mode laser with nearly diffraction-limited spatial profile. Linewidth measurement using a custom-made Fabry Perot interferometer revealed instrument-limited linewidth of <126> 5 MHz at 1064nm.

6 illus, 9 ref

021267   Ganguly N D;Iyer K N (Physics Dep, St Xavier's College, Ahmedabad-380 009, Email: ganguly.nandita@gmail.com) : Can El Nino induce stratosphere-troposphere exchange of ozone?. Curr Sci 2014, 106(6), 860-6.

The possibility of stratosphere-troposphere exchange (STE) of ozone induced by El Nino has been studied over the Indian region for two events spanning the periods April 1997-May 1998 and August 2006-February 2007 using in situ and satellite-based measurements. The response of STE to El Nino was observed to be opposite in the tropics and extra tropics. In the tropics, lifting of polluted, ozone-rich surface air led to reduced lower tropospheric and enhanced upper tropospheric and lower stratospheric ozone during the El Nino period, indicating transport from the troposphere into the stratosphere. Conversely, in the extra tropics, sinking motion from the stratosphere into the troposphere resulted in higher upper tropospheric ozone concentration during the El Nino period. An increase in the middle and lower tropospheric ozone during the La Nina period immediately following the El Nino period suggests that the response of STE to El Nino did not manifest concurrently with the period of El Nino, but lagged by several months. El Nino southern oscillation (ENSO)-induced changes in total ozone are more prominent in the extra tropics of the northeast, compared to northwest India. However, as vertical ozone profiles are available for only two El Nino events, and the ozone variability between El Nino and La Nina events are relatively small, more detailed studies are needed to understand the dynamic influence of ENSO in producing ozone variability in India.

8 illus, 30 ref

021266   Dhaman R K;Krishnakumar V;Pillai V P M; Satyanarayana M;Raghunath K (Optoelectronics Dep, Kerala Univ, Kariavattom, Trivandrum-695 581, Email: vpmpillai9@gmail.com) : Deriving aerosol scattering ratio using range-resolved lidar ratio. Pramana J Phys 2014, 82(2), 391-5.

Study on the optical characteristics of aerosol is carried out using the dual polarization lidar observations from the tropical inland station Gadanki (13.5°N, 79.2°E) for the period of observation during the year 2010. The summer and monsoon observation days show high scattering ratio at the tropical tropopause layer (TTL) and at the lower stratosphere region. The depolarization ratio is also high at this altitude due to the transport of particulates to the TTL layer by the active convection prevailing at the period. The study reveals more dependable values of scattering ratio that are seasonal and range-dependent.

2 illus, 7 ref

021265   Das S;Misra P;Vignesh G;Srivastava S B;Gahlot R;Agarwal N (Corporate R & D, Moser Baer India Ltd, , Greater Noida, Email: sthitadhi.das@moserbaer.net) : Effect of concentration, pH and temperature on the CdS film thickness deposited by CBD process. Invertis J renewable Energy 2013, 3(2), 118-124.

In this study authors have found the relation of pH, temperature and concentration of CdCl₂2 and thiourea on the film thickness. The thickness of CdS required for device grade solar cell is in the range of 50-60 nm. The thickness is dependent on the deposition time, deposition temperature, concentration of the cadmium and sulphur source, and pH. A study of the effect of each on the parameters on the thickness, transmittance and band gap will help in tuning the thickness, transmittance and band gap. So in this work we have found the relation for the thickness for each of the variable parameters.

9 illus, 13 ref

021264   Chaubey S;Kher S;Kishore J;Oak S M (NO, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: smita@rrcat.gov.in) : CO₂ laser-inscribed low-cost, shortest-period long-period fibre grating in B-Ge co-doped fibre for high-sensitivity strain measurement. Pramana J Phys 2014, 82(2), 373-7.

Developed high sensitivity long-period fibre gratings (LPGs) in B-Ge co-doped fibre for strain sensing application. These LPGs are shortest grating period (180 μm) LPGs inscribed in B-Ge co-doped fibre using CO₂ laser-based grating inscription set-up. Strain sensitivity of 1.77 dB/mε has been obtained for attenuation band corresponding to the turnaround point mode. TAP operation of LPG facilitates intensity-based detection using simple optical power meter instead of wavelength-based detection.

4 illus, 9 ref

021263   Chattopadhyay M;Kumbhakar P;Chatterjee U (Nanoscience Laboratory, Physics Dep, National Institute of Technology, Durgapur-713 209, Email: kumbhakarp@yahoo.com) : Observation of two-photon absorption at UV radiation in ZnS quantum dots. Pramana J Phys 2014, 82(2), 327-30.

Research studies on quantum dots (QDs) of semiconductor materials are of potential interest in present days having promising applications in different optoelectronic devices. Among other materials, ZnS is a direct bandgap semiconductor material having a wide bandgap of 3.6 eV for its cubic phase at room temperature and it shows excellent optical properties. However, here the nonlinear optical (NLO) properties of chemically synthesized ZnS QDs of average size of <126> 1.5 nm have been reported which are measured by using an indigenously developed Z-scan technique. The pump radiation is 355 nm which is the third harmonic of the Q-switched Nd:YAG laser radiation having pulsed duration of 10 ns with the repetition rate of 10 Hz. The measured experimental data have been analysed by using analytical models and two-photon absorption coefficients of the ZnS QDs at 355 nm have been extracted.

1 illus, 1 table, 10 ref

021262   Chakravarty U;Kuruvilla A;Singh R;Upadhyay B N;Bindra K S;Oak S M (Solid State Laser Div, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: ushac@rrcat.gov.in) : Linearly polarized intracavity passive Q-switched Yb-doped photonic crystal fibre laser. Pramana J Phys 2014, 82(2), 379-83.

In this paper author reported linearly polarized high average power passive Q-switched ytterbium-doped photonic crystal fibre laser with a Cr⁴⁺:YAG crystal as a saturable absorber. An average output power of 9.4 W with pulse duration of 64 ns and pulse repetition rate of 57.4 kHz with a slope efficiency of 52% was achieved. Measured polarization extinction ratio (PER) of the Q-switched laser output was 10.5 dB.

3 illus, 4 ref

021261   Botha L R;De Clercq L E;Smit A M;Botha N; Ronander E;Strydom H J (NO, CSIR, National Laser Centre, Meiring Naude Road,, Gauteng, Pretoria, RSA, Email: Lrbotha@csir.co.za) : Quantum coherent control of the vibrational dynamics of a polyatomic molecule using adaptive feedback control of a femtosecond laser. Pramana J Phys 2014, 82(2), 249-53.

Simulates adaptive feedback control to coherently shape a femtosecond infrared laser pulse by means of a 4f-spatial light modulator in order to selectively excite the rovibrational modes of a polyatomic molecule. We preferentially populate an arbitrarily chosen upper rovibrational level by only employing these tailored temporally shaped pulses. A second laser would then allow for mode selective chemistry to interact selectively with the excited population. Alternatively the excited molecules enhanced reactivity could be exploited for selective chemistry.

3 illus, 10 ref

021260   Boraste D R;Gupta M;Shankarling G;Ray A K; Nayak S K (Dyestuff Dep, Institute of Chemical Technology, Matunga, Mumbai-400 019, Email: gs.shankarling@ictmumbai.edu.in) : Spectroscopy and laser characterization of synthesized supramolecular host cucurbit[7]uril using aqueous rhodamine B dye. Pramana J Phys 2014, 82(2), 271-5.

Recent demonstration in augmenting the efficiency of aqueous Rhodamine dye lasers using cucurbit[7]uril (CB[7]), a deaggregating and photostabilizing host, has drawn interest in the synthesis and characterization of spectroscopic grade CB[7] in larger quantities. Synthesis of cucurbituril group of macrocycles always leads to the formation of various homologues of CB[n]s (n=5-7) with CB[7] as the minor product. The literature procedure has been optimized to get pure CB[7] in 12-14% yield by fractional crystallization and the purity was checked by NMR, MS and spectrophotometric titration. Laser performances of the synthesized and commercial CB[7] sample as an additive were evaluated using Nd-YAG (532 nm) pumped Rhodamine B aqueous dye lasers and comparable results were obtained.

6 illus, 3 ref

021259   Arulsamy A D (Condensed Matter Group, Interdisciplinary Science Div, , F-02-08 Ketumbar Hill, Jalan Ketumbar, 56100 Kuala-Lumpur, Malaysia, Email: sadwerdna@gmail.com) : Einstein-Podolski-Rosen paradox, non-commuting operator, complete wavefunction and entanglement. Pramana J Phys 2014, 82(3), 477-88.

Einstein, Podolski and Rosen (EPR) have shown that any wavefunction (subject to theSchr"odinger equation) can describe the physical reality completely, and any two observables associatedwith two non-commuting operators can have simultaneous reality. In contrast, quantum theoryclaims that the wavefunction can capture the physical reality completely, and the physical quantitiesassociated with two non-commuting operators cannot have simultaneous reality. The abovecontradiction is known as the EPR paradox. Here, we unambiguously expose that there is a hiddenassumption made by EPR, which gives rise to this famous paradox. Putting the assumption right thistime leads us not to the paradox, but only reinforces the correctness of the quantum theory. However, it is shown here that the entanglement phenomenon between two physically separated particles(they were entangled prior to separation) can only be proven to exist with a `proper' masurement.

12 ref

021258   Arora V;Chakravarty U;Singh M P;Chakera J A; Naik P A;Gupta P D (Laser Plasma Div, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: mpsingh@rrcat.gov.in) : Spectral analysis of K-shell X-ray emission of magnesium plasma produced by ultrashort high-intensity laser pulse irradiation. Pramana J Phys 2014, 82(2), 365-71.

Spectral analysis of K-shell X-ray emission of magnesium plasma, produced by laser pulses of 45 fs duration, focussed up to an intensity of <126>10¹⁸ W cm^-2, is carried out. The plasma conditions prevalent during the emission of X-ray spectrum were identified by comparing the experimental spectra with the synthetic spectra generated using the spectroscopic code Prism-SPECT. It is observed that He-like resonance line emission occurs from the plasma region having sub-critical density, whereas K-α emission arises from the bulk solid heated to a temperature of 10 eV by the impact of hot electrons. K-α line from Be-like ions was used to estimate the hot electron temperature. A power law fit to the electron temperature showed a scaling of I^0.47 with laser intensity.

5 illus, 6 ref

021257   Arora P;Awasthi A;Bharath V;Acharya A;Yadav S;Agarwal A;Gupta A S (Time and Frequency Div, CSIR-National Physical Laboratory, Dr K S Krishnan Road, New Delhi-110 012, Email: arorap@nplindia.org) : Atomic clocks: a brief history and current status of research in India. Pramana J Phys 2014, 82(2), 173-83.

Frequency corresponding to the energy difference between designated levels of an atom provides precise reference for making a universally accurate clock. Since the middle of the 20th century till now, there have been tremendous efforts in the field of atomic clocks making time the most accurately measured physical quantity. National Physical Laboratory India (NPLI) is the nation's timekeeper and is developing an atomic fountain clock which will be a primary frequency standard. The fountain is currently operational and is at the stage of complete frequency evaluation. In this paper, a brief review on atomic time along with some of the recent results from the fountain clock will be discussed.

3 illus, 57 ref

021256   Aniruddha Kumar;Bhatt R B;Behere P G;Afzal M; Arun Kumar;Nilaya J P;Biswas D J (NO, Advanced Fuel Fabrication Facility, Bhabha Atomic Research Centre, Tarapur-401 504, Email: dhruba8biswas@gmail.com) : Laser-assisted surface cleaning of metallic components. Pramana J Phys 2014, 82(2), 237-42.

Removal of a thin oxide layer from a tungsten ribbon and ThO₂ particulates from zircaloy surface was achieved using a pulsed Nd: YAG laser. The removal mechanism of the oxide layer from the tungsten ribbon was identified as spallation or sublimation depending on the wavelength and fluence of the coherent radiation. The oxidized and cleaned surfaces were analysed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Laser-cleaned tungsten ribbons were used in a thermal ionization mass spectrometer (TIMS) to determine isotopic composition of neodymium atoms. The fundamental (1064 nm) and the third harmonic (355 nm) radiations were found to be the most effective in removing ThO₂ particulates from the zircaloy surface. Decontamination efficiency was found to be critically dependent on the wavelength of the coherent radiation and number of exposures. The mechanism of cleaning of ThO₂ particulates from the zircaloy surface at different wavelengths of the incident radiation has been explained qualitatively.

3 illus, 3 ref

021255   Ananthakumar S;Jayabalan J;Singh A;Khan S; Prajapati S;Moorthy Babu S;Chari R (NO, Crystal Growth Centre, Anna Univ, Chennai-600 025, Email: jjaya@rrcat.gov.in) : Size-independent peak shift between normal and upconversion photoluminescence in MPA-capped CdTe nanoparticles. Pramana J Phys 2014, 82(2), 353-8.

In this article, author report size-dependent measurement of the shift in peak of upcon-version photoluminescence spectra compared to that of normal photoluminescence using a 800 nm femtosecond laser and its second harmonic. It has been shown that the upconversion photoluminescence is always red-shifted compared to that of normal PL in all the samples. By measuring the power-dependent upconversion photoluminescence (UCPL), it has been shown that the origin of UCPL from MPA-capped CdTe nanoparticles is mainly of two-photon absorption.

6 illus, 12 ref

021254   Altaf M;Ahmad M M (Physics Dep, National Institute of Technology, Hazratbal, Srinagar-190 006, Email: altafnig@rediffmail.com) : Estimation of magnetospheric plasma parameters from whistlers observed at low attitudes. Curr Sci 2014, 106(3), 417-24.

Whistler observations during night-time made at low-latitude Indian ground stations, Jammu (geomag. lat. 29°26'N; L = 1.17), Nainital (geomag. lat. 19°1'N; L = 1.16) and Varanasi (geomag. lat. 14°55'N; L = 1.11) are used to deduce electron temperature and electric field in the vicinity of the magnetospheric equator. The accurate curve-fitting and parameter estimation techniques are used to compute nose frequency and equatorial electron density from the dispersion measurements of short whistlers recorded at Jammu, Nainital and Varanasi. In this communication we estimate the magnetospheric electron temperature and electric field from the dispersion analysis of short whistlers observed at low latitudes using different methods; the results obtained are in good agreement with those reported by other workers. The upper atmosphere environment is impacted by energetic particles, solar radiation and interplanetary magnetic fields that drive 'space weather' disturbances in the region, leading to strong electric currents, order of magnitude changes in neutral density and temperature, and major redistribution of plasma. At the same time, circulation and variability of the upper atmosphere are dramatically impacted by waves carrying energy and momentum upward from hurricanes, thermal tides and surface features. This region is where space and Earth's atmosphere interact, forming a critical boundary that must be studied to advance our understanding of the whole Earth system.

4 illus, 1 table, 46 ref

021253   Alee K S;Rao D N (NO, School of Physics, Hyderabad Univ, Hyderabad-500 046, Email: shadakaleek@gmail.com) : Time-dependent micro-raman scattering studies of polyvinyl alcohol and silver nitrate thin films. Pramana J Phys 2014, 82(2), 425-31.

In-situ monitoring of silver nanoparticle formation was studied in thin films of poly-vinyl alcohol and silver nitrate. We proposed the observation of surface-enhanced Raman spec-troscopy (SERS) as a novel and simple technique to record the growth of silver nanoparticles in polyvinyl alcohol thin films. Observed enhancement in the Raman bands of polyvinyl alcohol is explained through the localized surface plasmon resonance of silver nanoparticles. Influence of temperature generated by silver nanoparticles on the formation of nanoparticles is also discussed.

3 illus, 24 ref

020209   Zhang S;Wang J;Peng A X;Cai B (Mathematics Dep, Bohai Univ, Jinzhou 121013, People's Republic of China, Email: zhshaeng@yahoo.com.cn) : Generalized exp-function method for multiwave solutions of Sine-Gordon equation. Pramana J Phys 2013, 81(5), 763-73.

In this paper, the exp-function method is generalized to sine-Gordon (sG) equation and single-, double- and three-wave solutions are obtained. It is shown that the generalized exp-function method combined with appropriate anstaz may provide a straightforward, effective and alternative method for constructing multiwave solutions of some nonlinear partial differential equations.

7 illus, 20 ref

020208   Zakharenko A A (NO, International Institute of Zakharenko Waves (IIZWs), 660037, Krasnoyarsk-37, 17701, Krasnoyarsk, Russia, Email: aazaaz@inbox.ru) : Fundamental modes of new dispersive SH-waves in piezoelectromagnetic plate. Pramana J Phys 2013, 81(5), 819-27.

Fundamental modes of new dispersive shear-horizontal (SH) acoustic waves propagating in the (6 mm) piezoelectromagnetic plate are studied. These SH-waves can propagate when the following boundary conditions are exploited for both the upper and lower surfaces of the plate: (1) when the surfaces are mechanically free, electrically and magnetically closed and (2) when the surfaces are mechanically free, electrically and magnetically open. The SH-waves depend on the electromagnetic wave speed VEM = 1/√(εμ) and can only exist when the electromagnetic constant a ≠ 0. The calculations (first evidence) were performed for the PZT-5H-Terfenol-D which is a composite with a large value of a. The limit cases of large values of α (α² = 0.5εμ, α² = 0.9εμ, and α² = 0.99εμ) are studied because they satisfy the limitation condition of α² <60> εμ.

1 illus, 1 table, 64 ref

020207   Ying W;Xiong Y (College of Science, Institute of Low Dimensional Materials and Technology, Civil Aviation, Tianjin 300300, China, Email: x-yang@cauc.edu.cn) : Phase transition properties of a cylindrical ferroelectric nanowire. Pramana J Phys 2013, 81(5), 873-83.

Based on the transverse Ising model (TIM) and using the mean-field theory, investigate the phase transition properties of a cylindrical ferroelectric nanowire. Two different kinds of phase diagrams are constructed and discuss systematically the effects of exchange interactions and the transverse field parameters on the phase diagrams. Moreover, the cross-over features of the parameters from the ferroelectric dominant phase diagram to the paraelectric dominant phase diagram are determined for the ferroelectric nanowire. In addition, the polarizations of the surface shell and the core are illustrated in detail by modifying the TIM parameters.

7 illus, 29 ref