³⁵Cl NQR frequency and spin lattice relaxation time in 3,4‐dichlorophenol as a function of pressure and temperature

Abstract

The pressure dependences of (35)Cl 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 Δm = ±1 and Δm = ±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.

35Cl NQR frequency and spin lattice relaxation study in 3,4‐dichloronitrobenzene as a function of temperature and pressure

“…By following the similar procedure used by Ramu et al and Suresh et al, the NQR data has been analyzed using Equations , and . The moment of inertia values are taken from the literatur .…”

“…The molten solid of mass about 2 g is taken in a glass ampoule of 10‐mm diameter and sealed to avoid hydration of the sample. Measurements of NQR frequency and spin lattice relaxation time (T 1 ) have been carried out using the set up described earlier in the temperature range 77 to 300 K. Two lines were observed throughout the temperature range studied and the frequency values at 77 K are in good agreement with those reported in the literature…”

“…Bayer proposed the first theoretical model to explain the temperature dependence of T 1 , which was later modified by Woessner and Gutowsky by defining an average lifetime for all the torsional states and obtained W 1 and W 2 for the Δm = ±1 and Δm = ±2 transitions. In the present case, we have followed the methods used by Ramu et al and Suresh et al for the analysis of spin lattice relaxation time.…”

“…The second term, the “dynamic term,” represents the effect of pressure on the amplitude of torsional oscillation. The methods followed for the analysis of pressure variation of NQR frequency is as described in the paper by Ramu et al and Suresh et al…”

Assessment of substituent effects on the parameters of 35Cl nuclear quadrupole resonance in para‐substituted benzene‐sulphenyl chloride via quantum chemical calculations

“…The first NQR measurements were reported for a solid using signals from 35 Cl in transdichloroethylene . 35 Cl NQR parameters of the many molecules were investigated for illustration of the structural details and the variations in the electronic environment of the nucleuses . In one study, correlation of 35 NQR coupling frequencies for some chlorobenzene has been investigated …”