Proton NMR Study of Molecular Dynamics in Hydrazinium Perchlorate

AbstractThe proton spin-lattice relaxation time T1 (at 5.4, 10 and 15 MHz) and second moment M2 (at 9.8 MHz) have been measured in hydrazinium Perchlorate (N2H5ClO4). The temperature dependence of T, shows two minima. The low temperature T, minimum has been explained in terms of NH3 reorientation about the N-N axis while the high temperature minimum is attributed to the exchange of protons within the NH2 group (180° flip about the H - N - H bisectrix). The activation energies for NH3 and NH: motions are found to be 20.5 kJ mol-1 and 39.8 kJ mol-1 , respectively. The second moment variation with temperature shows two transitions around 120 K and 210 K and has been discussed in terms of NH3/NH2 motions.

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Anomaly of the Proton Spin-Lattice Relaxation Time near the Critical Temperature of Dicalcium Lead Propionate Ca2Pb(C2H5COO)6

Journal of the Physical Society of Japan ◽

10.1143/jpsj.33.438 ◽

1972 ◽

Vol 33 (2) ◽

pp. 438-445 ◽

Cited By ~ 33

Author(s):

Itaru Tatsuzaki ◽

Koichi Sakata ◽

Isamu Tōdō ◽

Masaharu Tokunaga

Keyword(s):

Relaxation Time ◽

Critical Temperature ◽

Lattice Relaxation ◽

Lattice Relaxation Time ◽

Proton Spin ◽

Spin Lattice Relaxation ◽

Spin Lattice Relaxation Time ◽

Spin Lattice

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A nuclear magnetic resonance investigation of three solid benzenes

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1953.0123 ◽

1953 ◽

Vol 218 (1135) ◽

pp. 537-552 ◽

Cited By ~ 208

Keyword(s):

Crystal Structure ◽

Nuclear Magnetic Resonance ◽

Relaxation Time ◽

Lattice Relaxation ◽

Lattice Relaxation Time ◽

Spin Lattice Relaxation ◽

Second Moment ◽

Spin Lattice ◽

Second Moments ◽

A Value

The nuclear magnetic resonance absorption spectrum and the spin-lattice relaxation time have been measured for the protons in three isotopic species of benzene in polycrystalline form between 75 and 278° K. The three species were C 6 H 6 , C 6 H 5 D and 1. 3. 5 - C 6 H 3 D 3 . For all three species the measured spectrum has its full rigid lattice width below 90° K. A method of analysis is developed which makes it possible to derive separately the intramolecular and the intermolecular contributions to the second moment (mean square width) of the spectrum from the measured second moments, without the necessity of knowing the crystal structure. From the intramolecular contribution it is found that the separation of neighbouring protons in the C 6 H 6 molecule is 2.495 ± 0.018 Å. The intermolecular contribution is in agreement with a value calculated from a knowledge of the crystal structure. On warming from 90 to 120°K the spectrum for all three species narrows considerably. From 120°K to the melting-point (278.7° K) the second moments remain almost constant. The second moment separation procedure is also applied in this range and leads to the conclusion that the narrowing is caused by reorientation of the molecules about their hexad axes in the crystal lattice. Analysis of the measurements of the spin-lattice relaxation time shows that for all three species the reorientation process is governed by an activation energy of 3.7 ± 0.2 kcal/mole. The reorientation frequency is of the order of 10 4 c/s at 85° K and rises to a value of the order of 10 11 c/s just below the melting-point. The relationship between the present experimental results and recent measurements of the Raman spectrum of solid benzene is discussed. Finally, consideration is given to the application to other materials of methods of separating the intra- and intermolecular contributions to the second moment.

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