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The pressure dependences of Cl-35 nuclear quadrupole resonance (NQR) frequency, temperature and pressure variation of spin lattice relaxation time (T-1) were investigated in 3,4-dichlorophenol. T-1 was measured in the temperature range 77-300 K. Furthermore, the NQR frequency and T-1 for these compounds were measured as a function of pressure up to 5 kbar at 300 K. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities W-1 and W-2 for the Delta m = +/- 1 and Delta m = +/- 2 transitions were also obtained. A nonlinear variation of NQR frequency with pressure has been observed and the pressure coefficients were observed to be positive. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. An attempt is made to compare the torsional frequencies evaluated from NQR data with those obtained by IR spectra. On selecting the appropriate mode from IR spectra, a good agreement with torsional frequency obtained from NQR data is observed. The previously mentioned approach is a good illustration of the supplementary nature of the data from IR studies, in relation to NQR studies of compounds in solid state.

The temperature and pressure dependence of Cl-35 NQR frequency and spin lattice relaxation time (T-1) were investigated in 2,3-dichloroanisole. Two NQR signals were observed throughout the temperature and pressure range studied. T-1 were measured in the temperature range from 77 to 300 K and from atmospheric pressure to 5 kbar. Relaxation was found to be due to the torsional motion of the molecule and also reorientation f motion of the CH3 group. T-1 versus temperature data were analyzed on the basis of Woessner and Gutowsky model, and the activation energy for the reorientation of the CH3 group was estimated. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities were also obtained. NQR frequency shows a nonlinear behavior with pressure, indicating both dynamic and static effects of pressure. The pressure coefficients were observed to be positive for both the lines. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. The variation of spin lattice time with pressure was very small, showing that the relaxation is mainly due to the torsional motions of the molecules. Copyright (C) 2010 John Wiley & Sons, Ltd.

Various metal salts (Na, K, Rb, and NH4) of monochloro acetic acid were prepared and the Cl-35 nuclear quadrupole resonance frequencies were measured at room temperature. A comparative study of nuclear quadrupole resonance frequencies of monochloro acetic acid and its metal salts is carried out. The frequency shifts obtained in the respective metal chloroacetates are used to estimate the changes in the ionicity of C-Cl bond. Further, the changes in the ionicity of C-Cl bond were used to estimate the percentage of intra-molecular charge transfer between respective cation-anion of the metal salts of chloro acetic acid. The nuclear quadrupole resonance frequency is found to decrease with increasing ionicity of the alkali metal ion.

ZrN films were deposited by dc reactive magnetron sputtering on silicon substrates under optimized nitrogen partial pressure of $6 x 10^{-5}$ mbar. Structural, electrical and optical properties were systematically investigated. Films deposited at room temperature exhibited Schottky structure without any silicide interfacial layer. These films have electrical resistivity of $4.23 x 10^{-3}$ $\Omega$ cm, which were crystalline in nature, with cubic (1 1 1) orientation. Refractive index and extinction coefficient were found to be 1.95 and 0.43, respectively at a wavelength of 350 nm. Samples were annealed for 1 h in air at two temperatures, 350 and 550 $^oC.$ Scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDAX) showed alloy penetration pits. Extent of penetration was greater in the films, which were annealed at higher temperature $(550 ^oC).$ Variation in refractive index was observed in the range of 1.95–1.80 at 350 nm, for the annealed films, with increase in grain size from 7.25 to 11.10 nm. Poly-crystalline nature has been observed with (1 1 1) and (2 0 1) orientations. Resistivity is found to increase from $4.23 X 10^{-3}$ to $6.21 X 10^{-3} \Omega cm.$

This paper deals with the preparation of Zirconium Nitride films by DC reactive magnetron sputtering. Films were deposited on silicon substrates at room temperature. Nitrogen partial pressure was varied from $4 \times 10^{-5} to 10 \times 10^{-5}$ m bar and the effect on the structural, electrical, optical properties of the films was systematically studied. The films formed at a nitrogen pressure of $6 \times 10^{-5}$ mbar showed low electrical resistivity of $1.726 \times 10^{-3} \Omega . cm.$ The deposited films were found to be crystalline with refractive index and extinction coefficient 1.95 and 0.4352 respectively.

An ESR study of ClO3 centres in x-irradiated ammonium perchlorate (NH4ClO4) single crystals is carried out that is aimed at resolving the controversy that has recently arisen over the possible occurrence of low-temperature phase transitions in the compound (room temperature structure: orthorhombic; space group Pnma). The ESR spectra are recorded as a function of the orientation of the magnetic field H in the three orthogonal crystallographic planes at 300 K, 77 K, and 4.2 K, and also as a function of temperature for H parallel to the principal z-component A(zz)(Cl) of the Cl-35 hyperfine coupling tenser. The analysis of the spectra shows that while the g-tensor remained axial over the entire temperature range (g(parallel to) = 2.0052(3), 2.0055(3), 2.0057(3) and g(perpendicular to) = 2.0090(3), 2.0096(3), 2.0105(3) at 300 K, 77 K, and 4.2 K respectively), A(Cl), which is rhombic at room temperature (A(zz) = 429.77(1.0) MHz, A(yy) = 316.15(1.0) MHz, and A(xx) = 325.98(1.0) MHz at 300 K) becomes more axial as the temperature is lowered (A(zz) = 441.90(1.0) MHz, A(yy) = 299.09(1.0) MHz, and A(xx) = 301.61(1.0) MHz at 77 K, and A(zz) = 445.55(1.0) MHz, A(yy) = 299.84(1.0) MHz, and A(xx) = 303.43(1.0) MHz at 4.2 K). No changes in the spectra attributable to any phase transition were observed, and we conclude that NH4ClO4 does not undergo any phase transition below room temperature. Furthermore, it is found that during ClO4- --> ClO3 radiative decomposition the mirror-related Cl-O bonds, even though weaker than the other Cl-O bonds, do not break, thus confirming our earlier conclusion that mirror symmetry is preserved during radiation damage.