Electron spin resonance studies of radicals condensed from irradiated water vapor: paramagnetic relaxation of trapped electrons in ice

1969 ◽  
Vol 47 (12) ◽  
pp. 2155-2160 ◽  
Author(s):  
P. Wardman ◽  
W. A. Seddon
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Trap Depth ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Spin Resonance ◽  
Fast Passage

The spin–lattice relaxation time T1 of electrons (et−) trapped in several ice matrices at 77 °K has been estimated to be of the order of 10−2 s by observation of the electron spin resonance (e.s.r.) dispersion signal under fast passage conditions. These studies, together with measurements of the microwave power saturation of the e.s.r. absorption signal indicate that there is little difference in T1 at 77 °K for et− in solute-free polycrystalline H2O or D2O ice, γ-irradiated 8 M NaOH/H2O or NaOD/D2O glassy ices, and in 8 M NaOD/D2O glasses in which the electrons were produced by photoionization of ferrocyanide ion. This indicates that the predominant spin–lattice relaxation mechanism is not cross relaxation, and that correlations between T1 and line width or trap depth are inappropriate.

Recombination of Optically Excited Carriers in a-Si:H at Low temperatures and Intermediate Times

2002 ◽  
Vol 715 ◽  
Author(s):  
J. Whitaker ◽  
T. Su ◽  
P. C. Taylor
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperatures ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Dipolar Relaxation ◽  
Spin Lattice ◽  
Carrier Recombination ◽  
Nmr Data ◽  
Spin Resonance ◽  
Time Regime

AbstractOptically induced electron spin resonance (LESR) studies on time scales in between the previously published PL and LESR results (approximately 10 ms to 10 s) allow one to examine the cross over between energy-loss (downward) hopping of carriers and carrier recombination via tunneling. In addition, data in this time regime are directly compared in the same sample with NMR data on the dipolar spin-lattice relaxation of the bonded hydrogen where light induced electrons and holes are responsible for dipolar relaxation of bonded hydrogen. The LESR results confirm the interpretation of the NMR measurements.

A nuclear magnetic resonance investigation of solid tetraphosphorus trisulphide

1978 ◽  
Vol 364 (1719) ◽  
pp. 553-567 ◽  
Keyword(s):  
Phase 1 ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Minor Role ◽  
High Resolution Spectrum ◽  
Basal Nuclei ◽  
Spin Lattice ◽  
A Minor

The 31 P n. m. r. spectrum and spin–lattice relaxation time in polycrystalline P 4 S 3 have been measured between 77 and 500 K in the range 7 to 25 MHz. In phase II the 31 P n. m. r. spectra and second moments are dominated by the anisotropic chemical shift interactions. Close to the first-order phase transition at 314 K the spectra are narrowed by reorientation of the molecules about their triad axes. This motion also generates anisotropicshift spin-lattice relaxation notable for its absence of frequency dependence. The activation energy of this motion was found to be 34 kJ mol -1 . Nuclear dipolar interactions play only a minor role. In phase 1 the molecules exhibit rapid quasi-isotropic reorientation and diffusion. The anisotropic broadening interactions are averaged out and an AB 3 high-resolution spectrum of a doublet and quartet are resolved at 420 K, well below the melting point, 446 K. In this phase the spin–rotation interaction relaxation mechanism becomes dominant. Taking advantage of the remarkable motional narrowing in this compound we report the first solid-state n. m. r. J spectrum. This spectrum, recorded at 410 K, allowed the J coupling between apical and basal nuclei in solid P 4 S 3 to be measured accurately, 70.4 ± 0.5 Hz.

1HNMR Study on the Motion of NH4+ in Ferroelectric NH4H(ClH2CCOO)2 and Mixed (NH4)1-xRbxH(ClH2CCOO)2 (x = 0.15)

2002 ◽  
Vol 57 (11) ◽  
pp. 883-887 ◽  
Author(s):  
M. Zdanowska-Fra̡czek ◽  
A. Kozaka ◽  
R. Jakubasb ◽  
J. Wa̡sickia ◽  
R. Utrechta
Keyword(s):  
Relaxation Time ◽  
Group Dynamics ◽  
Nmr Relaxation ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Temperature Dependent ◽  
Spin Lattice

Temperature-dependent proton NMR relaxation time measurements have been performed at 60 MHz in order to study the NH4+ dynamics in ferroelectric NH4H(ClH2CCOO)2 and mixed Rbx(NH4)1-x(ClH2CCOO)2, where x = 0.15. The data indicate that the dominant relaxation mechanism for the NMR spin-lattice relaxation time T 1 in both crystals involves simultaneous NH4 group reorientation about their C2 and C3 symmetry axis in the paraelectric phase. Details of the NH4+reorientation have been inferred from analysis of temperature dependence of T1 assuming the Watton model. The activation parameters of the motionshave been determined.It has been found that the substitution of Rb does not change the activation parameters of the NH4 group dynamics.

Sign in / Sign up

Export Citation Format

Share Document