Temperature- and pressure-dependent study of 35Cl NQR frequency and spin lattice relaxation time in 2,3-dichloroanisole

2010 ◽  
pp. n/a-n/a ◽  
Author(s):  
L. Ramu ◽  
K. P. Ramesh ◽  
D. Ramananda ◽  
R. Chandramani
1992 ◽  
Vol 47 (1-2) ◽  
pp. 330-332 ◽  
Author(s):  
A. D. Gordeev ◽  
G. B. Soifer ◽  
A. P. Zhukov

AbstractThe 35Cl NQR frequency and spin-lattice relaxation time of solid chlorobenzene and chloropentafluorobenzene at temperatures from 77 K to the melting points have been measured and explained by thermoactivated librations and reorientations of the molecules around the normal to their plane. The activation energies of these motions have been estimated


1971 ◽  
Vol 49 (19) ◽  
pp. 2389-2395 ◽  
Author(s):  
Robin L. Armstrong ◽  
Douglas F. Cooke

Measurements of the temperature and pressure variation of the 35Cl nuclear spin–lattice relaxation time in Rb2PtCl6 and Cs2PtCl6 are reported. The spin–lattice relaxation time is measured at atmospheric pressure for temperatures from 60 to 500 K and at four temperatures between 290 and 380 K for pressures to 5000 kg cm−2. Previously published data for K2PtCl6 are also included in the discussion. The Van Kranendonk theory of nuclear quadrupolar relaxation forms the basis of the analysis. The rotary lattice mode frequencies are deduced; they are of approximately the same magnitude and increase in the same sequence as the frequencies deduced from nuclear quadrupole resonance frequency measurements and from infrared and Raman data. An analysis of the pressure dependence of the spin–lattice relaxation time data yields order of magnitude pressure coefficients for the rotary mode frequencies. Finally, a thermodynamic analysis, which takes specific volume effects into account by incorporating both the temperature and pressure dependence of the data, is presented.


1978 ◽  
Vol 39 (C6) ◽  
pp. C6-1215-C6-1216
Author(s):  
H. Ahola ◽  
G.J. Ehnholm ◽  
S.T. Islander ◽  
B. Rantala

1978 ◽  
Vol 56 (10) ◽  
pp. 1386-1389
Author(s):  
Marie D'Iorio ◽  
Robin L. Armstrong

The pressure-induced polymorphic phase transition at about 4 k bar in rubidium iodide was studied using nuclear magnetic resonance. The signature of the structural transition is a loss of echo intensity which presumably is due to an increase in the number of lattice defects as a result of the transition. The ratio of the spin–spin relaxation times of the iodine nuclei in the two phases is in agreement with the ratio predicted by a second moment calculation. The actual experimental values, however, are considerably smaller than the theoretical predictions signifying the migration of lattice defects. Estimates of the iodine spin–lattice relaxation time at atmospheric pressure indicate the necessity to include both an anharmonic Raman contribution and a covalency factor. The change in spin–lattice relaxation time with pressure as measured in the low pressure phase is dominated by the change in the lattice parameter. At the critical pressure the spin–lattice relaxation time decreases by a fractional amount which is approximately equal to the fractional volume change characterizing the transition. The pressure derivative of the spin–lattice relaxation time in the high pressure phase is nearly equal to that in the low pressure phase.


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