The temperature dependence of 35Cl NQR spectrum and study of spin—lattice relaxation times in chloral hydrate

1989 ◽  
Vol 192 (3-4) ◽  
pp. 379-382 ◽  
Author(s):  
J. Kasprzak ◽  
J. Pietrzak ◽  
A. Pietrzak
Keyword(s):  
Temperature Dependence ◽  
Chloral Hydrate ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
35Cl Nqr

Bonded Hydrogen and Trapped H2 in a-Si1−xGex:H Alloys

1989 ◽  
Vol 149 ◽  
Author(s):  
E. J. Vanderheiden ◽  
G. A. Williams ◽  
P. C. Taylor ◽  
F. Finger ◽  
W. Fuhs
Keyword(s):  
Temperature Dependence ◽  
Molecular Hydrogen ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
H Nmr ◽  
Local Environments

ABSTRACT1H NMR has been employed to study the local environments of bonded hydrogen and trapped molecular hydrogen (H2) in a series of a-Si1−xGex:H alloys. There is a monotonic decrease of bonded hydrogen with increasing x from ≈ 10 at. % at x = 0 (a-Si:H) to ≈ 1 at. % at x = 1 (a-Ge:H). The amplitude of the broad 1H NMR line, which is attributed to clustered bonded hydrogen, decreases continuously across the system. The amplitude of the narrow 1H NMR line, which is attributed to bonded hydrogen essentially randomly distributed in the films, decreases as x increases from 0 to ≈ 0.2. From x = 0.2 to x ≈ 0.6 the amplitude of the narrow 1H NMR line is essentially constant, and for x ≥ 0.6 the amplitude decreases once again. The existence of trapped H2 molecules is inferred indirectly by their influence on the temperature dependence of the spin-lattice relaxation times, T1. Through T1, measurements it is determined that the trapped H2 concentration drops precipitously between x = 0.1 and x = 0.2, but is fairly constant for 0.2 ≤ x ≤ 0.6. For a-Si:H (x = 0) the H2 concentration is ≈ 0.1 at. %, while for x ≥ 0.2 the concentration of H2 is ≤ 0.02 at. %.

scholarly journals The Motion of the OH Group in p-Chlorophenol and its Influence on the 35Cl NQR Parameters

1986 ◽  
Vol 41 (1-2) ◽  
pp. 408-411 ◽  
Author(s):  
Mariano J. Zuriaga ◽  
Carlos A. Martin
Keyword(s):  
Activation Energy ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Frequency Difference ◽  
Spin Lattice Relaxation ◽  
Normal Behaviour ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
Two Temperature ◽  
Nqr Parameters

The 35Cl NQR transition frequencies and the spin-lattice relaxation times, T1, for both lines in p-chlorophenol have been measured in the temperature range 90 - 310 K. The frequency difference and the temperature derivatives for both lines clearly show the existence of two temperature intervals with distinct lattice contributions to the EFG. Similarly, T1, data show a normal behaviour due to spin-phonon interactions up to 240 K. Above this temperature T1 begins to shorten in an exponential manner. The hindered motions of the OH group are proposed as responsibles of these effects, and an activation energy of 26 kJ mol-1 is determined.

35Cl NQR Studies of Bismuth Trichloride

1997 ◽  
Vol 52 (8-9) ◽  
pp. 614-620
Author(s):  
P. K. Babu ◽  
J. Ramakrishna
Keyword(s):  
Temperature Dependence ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Positive Temperature Coefficient ◽  
Spin Lattice Relaxation ◽  
Positive Temperature ◽  
Lattice Vibrations ◽  
Spin Lattice ◽  
Quadrupole Resonance ◽  
35Cl Nqr

Abstract The temperature dependence of the 35Cl nuclear quadrupole resonance (NQR) frequency and spin lattice relaxation time (T1) are studied in crystalline BiCl3 , in the range 40-300 K. The positive temperature coefficient observed for one of the 35Cl resonances is explained in terms of the strong intermolecular interactions that exist in this compound. Variation of with temperature is found to be similar at the chemically inequivalent halogen sites. Semiclassical descriptions based on torsional oscillator dynamics are found to be inadequate for explaining the spin lattice relaxation. T1 (T) data follow an AT2 + BT3 type behaviour, indicating that the anharmonic nature of the lattice vibrations plays a significant role in determining the temperature dependence of T1 at high temperatures.

Hydrogen Isotope Effect on the Temperature Dependence of the 35Cl-NQR Frequency in (NH4)2IrCl6

2002 ◽  
Vol 57 (6-7) ◽  
pp. 504-508 ◽  
Author(s):  
Yoshio Kume ◽  
Tetsuo Asaji
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Ammonium Ion ◽  
Energy Separation ◽  
Rotational States ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
Deuterated Analogue ◽  
Hydrogen Isotope Effect

The 35Cl-NQRfrequencies and spin-lattice relaxation times of (NH4)2IrCl6 and (ND4)2IrCl6 were measured in the temperature range 4.2 - 300 K. It was confirmed that no phase transition takes place down to 4.2 K. The observed frequency at 4.2 K in (ND4)2IrCl6 was higher by 18 kHz than that in the non-deuterated analogue. This discrepancy was attributed to a difference between the lowest rotational states of the ammonium ions in these compounds. The energy separation between the ground state and excited state of rotational motion, in which N-H of the ammonium ion rotates among the three directions slightly apart from the triad axis, was estimated by fitting analysis to be 31 cm-1 and 93 cm-1 for (ND4)2IrCl6 and (NH4)2IrCl6, respectively. The activation energy of the reorientation of the ammonium ion among the four directions of the triad axis was estimated to be 6.9 and 7.6 kJ mol-1, respectively

A 35CL NQR Spin-Lattice Relaxation Study on the Motion of D4h Anions in [C(NH2)3]2PdCl4, [C(NH2)3]2PtCl4, and [C(NH2)3]AuCl4

1986 ◽  
Vol 41 (1-2) ◽  
pp. 416-420
Author(s):  
Yoshihiro Furukawa ◽  
Daiyu Nakamura
Keyword(s):  
Relaxation Times ◽  
Sharp Decrease ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Dependent ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
The One ◽  
Increasing Temperature ◽  
Complex Anions

The temperature dependence of 35Cl NQR spin-lattice relaxation times T1ClQ was observed for the crystal of the title complexes. For the Pd(II) and Pt(II) complexes, the log T1ClQ vs. 103 T-1 curves having gentle positive gradients at lower temperatures decreased sharply with increasing temperature from ca. 150 and ca. 130 K, respectively. This sharp decrease of T1ClQ can be explained by the C4 reorientation of the D4h complex anions with the activation energy Ea of 34 kJ mol-1 for the former and 29 kJ mol-1 for the latter complex. These values agree well with those estimated from 1H T1 showing temperature dependent dipolar-quadrupolar cross relaxation. For the Au(III) salt, two of four 35Cl NQR lines showed a sharp decrease in T1ClQ from ca. 270 K, suggesting the onset of the C4 reorientation of the one kind crystallographically equivalent anions with Ea of 67 kJ mol-1.

A 35Cl NQR Study on Exchange Interactions between Paramagnetic [IrCl6]2– Ions

2002 ◽  
Vol 57 (6-7) ◽  
pp. 431-434 ◽  
Author(s):  
Hiroshi Miyoshi ◽  
Keizo Horiuchi ◽  
Ryuichi Ikeda
Keyword(s):  
Relaxation Times ◽  
Exchange Interactions ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
Temperature Dependences ◽  
Field Fluctuations ◽  
Paramagnetic Ions ◽  
Exchange Parameters

The 35Cl and 37Cl NQR frequencies and spin-lattice relaxation times T1Q in paramagnetic M2IrCl6 (M = NH4, Cs) were measured at 4 - 350 K. The observed temperature dependences were attributed to EFG fluctuations caused by lattice vibrations and magnetic field fluctuations caused by paramagnetic ions. The exchange parameters in the NH4 and Cs salts were calculated from 35Cl NQR T1Q to be 8.6 K and 1.8 K respectively. 37Cl data yielded 9.1 K and 2.1 K respectively. The obtained lattice constant dependence of J values was explained by considering Ir-Cl Cl-Ir superexchange interaction

Activation Energies for Fluxional Behavior in Aryl(pentachlorocyclopentadienyl)mercurials, η1 -C5Cl5 HgR, from 35Cl NQR Relaxation Times

1990 ◽  
Vol 45 (3-4) ◽  
pp. 503-510 ◽  
Author(s):  
Norbert Weiden ◽  
Alarich Weiss ◽  
Gary Wulfsberg ◽  
William Ilsley ◽  
William Ilsley ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
C Nmr ◽  
Phenyl Mercury

Abstract Solid-state activation energies for fluxional behavior in three aryl-subsituted (pentachlorocyclo-pentadienyl)phenylmercury compounds RHgC5 Cl5 : (pentachlorocyclopentadienyl)(pentamethyl-phenyl)mercury (I, R = C6 (CH3)5 , Eact = 19.3 kJ mol-1); (pentachlorocyclopentadienyl)(2,4,6-tris-(terf-butyl)phenyl)mercury (II, R = 2,4,6-C 6 H 2 (C(CH3)3)3 , Eact = 59.5 kJ mol-1); and (pentachloro-cyclopentadienyl)(phenyl)mercury (III, R = C6H5 , E act = 62.8 kJ mol-1) have beeb obtained from 35Cl NQR spin-lattice relaxation-time measurements. II has also been shown to be fluxional in solution by 13C NMR spectra. II was prepared by an exchange reaction between Hg(C5Cl5)2 and Hg(2,4,6-C6H2(C(CH3)3)3)2 , which reacted readily despite the great steric hindrance present in the latter reagent.

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