NOPR Collection:

First order molecular hyperpolarizabilities and intramolecular charge transfer from vibrational spectra of NLO material: 2,6-dichloro-4-nitroaniline

2013-09-02T16:34:07Z

Title: First order molecular hyperpolarizabilities and intramolecular charge transfer from vibrational spectra of NLO material: 2,6-dichloro-4-nitroaniline Authors: Janaki, A; Balachandran, V; Lakshmi, A Abstract: Vibrational spectral analysis of the non-linear optical (NLO) material, 2,6-dichloro-4-nitroaniline (DCNA) has been carried out by using FT-IR and FT-Raman spectroscopic techniques. The Hartree-Fock(HF) and Density Functional Theoretical (DFT) computations have been performed at 6-311++G** level to derive equilibrium geometry, vibrational wavenumbers, intensities and first order hyperpolarizability. The optimized geometry, various bonding features and harmonic vibrational frequencies of DCNA have been investigated. Vibrational bands to the various structural groups and their significance were investigated by analyzing the vibrational spectra. Vibrational analysis reveals that simultaneous IR and Raman activation to the phenyl ring modes also provide evidence for the charge transfer interaction between the donors and acceptor can make the molecule polarized and the intramolecular charge transfer interaction must be responsible for the NLO properties of DCNA. The Mulliken atomic charge analysis was also made in the present study. The dipole moment (m), polarizability (a) and the hyperpolarizability (β) values of the investigated molecule have been computed using HF and B3LYP methods. Page(s): 601-614

Non-linear propagation of electrostatic waves in relativistic Fermi plasma with arbitrary temperature

2013-09-02T16:34:43Z

Title: Non-linear propagation of electrostatic waves in relativistic Fermi plasma with arbitrary temperature Authors: Chandra, Swarniv; Ghosh, Basudev Abstract: Modulational instability of electron plasma waves has been investigated by using the quantum hydrodynamic (QHD) model for quantum plasma at finite temperature by deriving a non-linear Schrödinger equation including relativistic effects. It is shown that the electron degeneracy parameter and streaming velocity significantly affect the linear and non-linear properties of electron plasma waves in a finite temperature quantum plasma. Page(s): 627-633

Effect of ceramic material on heat dissipation from multi-stage depressed collector used in high efficiency traveling-wave tubes

2013-09-02T16:35:02Z

Title: Effect of ceramic material on heat dissipation from multi-stage depressed collector used in high efficiency traveling-wave tubes Authors: Gahlaut, Vishant; Sharma, R K; Srivastava, V; Alvi, P A; Ghosh, S K Abstract: To increase reliability, the thermal and structural integrity of a multi-stage depressed collector (MDC) used in traveling wave tubes (TWTs) has been improved. Highly reliable TWTs can be achieved by careful consideration of design requirements and constraints, material selection, weight reduction and cost effectiveness. In a TWT, maximum heat generated in MDC is due to maximum power dissipation and, hence, needs for proper thermal management. In the present paper, the thermal characteristics of MDC for different ceramic insulator materials have been studied. Page(s): 657-660

New grounded inductor simulator using unity gain cells

2013-09-03T16:34:23Z

Title: New grounded inductor simulator using unity gain cells Authors: Alpaslan, Halil; Yuce, Erkan Abstract: A new grounded inductor simulator employing unity gain cells with X terminal intrinsic resistors and a capacitor is proposed in the present paper. It has two voltage followers with X terminal intrinsic resistors, one current follower with X terminal intrinsic resistor and one floating capacitor which can be easily implemented in now-a-days technologies. Also, the inductance of the proposed simulated inductor can be adjusted externally by changing control voltages; accordingly, it is suitable for integrated circuit fabrication. Simulation and experimental test results are included to verify the claimed theory. Page(s): 651-656