35Cl NQR Study of Thermoactivated Motions of Nitro Groups in Picryl Chloride

1996 ◽  
Vol 51 (5-6) ◽  
pp. 713-715 ◽  
Author(s):  
Igor A. Kyuntsel
Keyword(s):  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Rapid Decrease ◽  
Spin Lattice Relaxation ◽  
Deep Minimum ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
Temperature Dependences ◽  
Picryl Chloride

Abstract The temperature dependences of the 35Cl NQR frequency (ν), spin-lattice relaxation time (T1), and spin-spin relaxation time (T2) have been studied in 2,4,6-trinitrochlorobenzene (picryl chloride) from 77 K up to the melting point (354 K). The T1(T) curve exhibits a pronounced composite mimimum near 300 K which gives evidence for the reorientations of the two ortho-NO2 groups around their two-fold symmetry axes with the activation energies of 27.4 kJ mol - 1 and 31.2 kJ mol - 1. These values can be related to the ortho-NO2 groups having the twist angles of 33° and 81°, respectively (the crystal structure of picryl chloride is known). The T2(T) dependence exhibits interesting features, too: a deep minimum about 140 K and a new rapid decrease above 270 K.

35Cl NQR and Molecular Motion in Solid C6X5Cl (X = H, F)

1992 ◽  
Vol 47 (1-2) ◽  
pp. 330-332 ◽  
Author(s):  
A. D. Gordeev ◽  
G. B. Soifer ◽  
A. P. Zhukov
Keyword(s):  
Relaxation Time ◽  
Molecular Motion ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Melting Points ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
35Cl Nqr

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

1H and 19F NMR Study of Ammonium Ion Motion in Ammonium Trifluorostannate (II)

1988 ◽  
Vol 43 (2) ◽  
pp. 187-188
Author(s):  
Kiyofumi Hirokawa ◽  
Yoshihiro Furukawa
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Ammonium Ion ◽  
Ion Motion ◽  
Spin Lattice ◽  
Nmr Study ◽  
Temperature Dependences

Abstract The temperature dependences of the second moment and spin-lattice relaxation time of 1H and 19F NMR were measured on ammonium trifluorostannate (II) NH4SnF3. It was found that the NH4+ ions having a C3 symmetry in the crystal undergo overall reorientations with an activation energy of 22 kJ mol - 1.

scholarly journals 79Br Nuclear Quadrupole Relaxation in the High Temperature Modification of Niobium Pentabromide

1992 ◽  
Vol 47 (6) ◽  
pp. 713-720 ◽  
Author(s):  
Noriaki Okubo ◽  
Harutaka Sekiya ◽  
Chiaki Ishikawa ◽  
Yoshihito Abe
Keyword(s):  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
35Cl Nqr ◽  
High Temperature Modification ◽  
Nuclear Quadrupole Relaxation

AbstractThe spin-lattice relaxation time of 79Br NQR has been measured between 4.2 K and room temperature. The result is compared with that of 35Cl NQR in NbCl5. The origin of the relaxation is attributed to the quadrupolar interaction and the temperature dependence is explained by the Raman process. The Debye temperature is determined to be 94 K and the relaxation time is related with the NQR frequency through the covalency.

Low Temperature Isotope Effect in Ammonium Hexachloroselenate(IV) Studied by 35Cl NQR

1994 ◽  
Vol 49 (1-2) ◽  
pp. 297-301 ◽  
Author(s):  
Y. Kume ◽  
T. Asaji ◽  
R. Ikeda
Keyword(s):  
Relaxation Time ◽  
Phase Transitions ◽  
Low Temperature ◽  
Transition Point ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Soft Modes ◽  
35Cl Nqr

Abstract The temperature dependence o f the 35Cl NQR frequency and spin-lattice relaxation time T1Q of (NH4)2SeCl6 and (ND4)2SeCl6 were measured from 400 K to 24.8 and 53.8 K, respectively. The disappearance of NQR signals in the low temperature region of both salts is attributed to phase transitions. We concluded from the temperature behavior of just above the transition point that the operative mechanism o f the transition is different in these salts: The transition of (ND4)2SeCl6 seems to be associated with rotary soft modes, while in the natural salt non-rotary soft modes seem to play an important role at the transition.

1H NMR Studies on Cationic Motions in Solid tert-Butylammonium Hexachlorostannate (IV)

1992 ◽  
Vol 47 (10) ◽  
pp. 1087-1090
Author(s):  
Hiroyuki Ishida ◽  
Tatsuo Higashiyama ◽  
Naomi Hayama ◽  
Ryuichi Ikeda
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Temperature Dependences

AbstractThe temperature dependences of the 1H spin-lattice relaxation time (T1) and the second moment (M2) of NMR absorptions were measured for anhydrous tert-butylammonium hexachlorostannate(IV) and its partially deuterated analogs [(CD3)3CNH3]2SnCl6 and [(CH3)3CND3]2SnCl6. Three kinds of cationic motions were revealed: the reorientations of the CH3 group about their C - C bonds, the NH+3 group about its C - N bond, and the tert-butyl group about the C - N bond. Their motional parameters were determined. Among the three motions, the NH+3 motion occurs at the lowest temperature with quite a small activation energy (9.9-10.0 kJ mol-1 ) .

scholarly journals 35Cl NQR, 1H NMR, and X-Ray Diffraction Studies in a Hydrogen Bonded Complex Na2PtCl6 · 6H2O

1998 ◽  
Vol 53 (6-7) ◽  
pp. 603-607 ◽  
Author(s):  
Hiroshi Miyoshi ◽  
Keizo Horiuchi ◽  
Narumi Sakagami ◽  
Kenichi Okamoto ◽  
Ryuichi Ikeda
Keyword(s):  
Relaxation Time ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Lattice ◽  
Temperature Dependences

Abstract The 35Cl NQR frequencies, spin-lattice relaxation time and 1H NMR relaxation time were measured on crystalline Na2PtCl6 • 6H2O at 77-350 K. The presence of three nonequivalent chlorine sites found by X-ray diffraction measurement is in agreement with the observed three NQR lines, which have different temperature dependences attributable to differences in the direction of H-bonding with water molecules. The three NQR lines correspond to three kinds of chlorines with different Pt-Cl distances and H-bond directions.

A Phase Transition and Molecular Dynamics in Crystalline C6H5CHCI2 by 35Cl NQR Investigations

1986 ◽  
Vol 41 (1-2) ◽  
pp. 275-278 ◽  
Author(s):  
I. A. Kjuntsel ◽  
V. A. Mokeeva ◽  
G. B. Soifer ◽  
I. G. Shaposhnikov
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Reorientational Motion ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
Second Order Phase Transition

The NQR frequency ν and the spin-lattice relaxation time T1 of 35Cl nuclei in crystalline (ω,ω)-dichlorotoluene, C6H5CHCl2, have been measured at temperatures above 77 K. The existence of a second-order phase transition was discovered at Tc = 94 K. At this point the low-temperature NQR spectrum consisting of five lines passes into the high-temperature doublet. The behaviour of ν and T1 as functions of temperature near the critical point Tc is investigated and corresponding parameters are obtained. The NQR signals fade out about 185 K due to the reorientational motion with the potential barrier of 33.9 kJ/mole.

scholarly journals Unusual Temperature Dependence of 35Cl NQR Spin-Lattice Relaxation Time in [(CH3)4N]2[MCl6] (M = Pb, Sn, Te)

1991 ◽  
Vol 46 (9) ◽  
pp. 809-814
Author(s):  
Yoshihiro Furukawa ◽  
Yoshihisa Baba ◽  
Shin-ei Gima ◽  
Makoto Kaga ◽  
Tetsuo Asaji ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Unit Cell ◽  
Spin Lattice Relaxation ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
Temperature Dependences

Abstract The temperature dependence of the spin-lattice relaxation time (T1H) of 1H NMR measured in tetramethylammonium hexachloroplumbate(IV), (Me4N)2[PbCl6], showed a deep and a shallow minimum near 190 and 115 K, respectively. Since the presence of two kinds of crystallographically nonequivalent cations in the room-temperature Fd 3c unit cell has been reported, the deep T1H minimum was assigned to the overall reorientation of three quarters of the Me4N+ ions and the shallow minimum to that of the remaining cations. Two different temperature dependences of the chlorine NQR spin-lattice relaxation time (T1Q), attributable to a modulated electric-field-gradient by the protonic motion, were observed in (Me4N)2[MCl6] (M = Pb, Sn, Te). One is found in the Pb complex whose T1Q stems from the cationic motion responsible for the deep T1H minimum, and the other one is determined by the cationic motion giving the shallow T1H minimum. Although all room-temperature phases of these complexes are well described by the Fd 3c unit cell, the presence of different temperature dependences of T1Q suggests that the CH3 groups in the respective complexes take different orientations in the crystals

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