Hiyam's Journal Update

Phys. Rev. B 76, 245209 (2007)
1H NMR electron-nuclear cross relaxation in thin films of hydrogenated amorphous silicon
Tining Su and P. C. Taylor, G. Ganguly and D. E. Carlson, D. C. Bobela, P. Hari

Abstract:
We investigate the spin-lattice relaxation of the dipolar order in 1H NMR in hydrogenated amorphous silicon (a-Si:H). We find that the relaxation is dominated by the cross relaxation between the hydrogen nuclei and the paramagnetic states. The relaxation is inhomogeneous, and can be described as a stretched exponential function. We proposed a possible mechanism for this relaxation. This mechanism applies to a rather broad range of paramagnetic states, including the deep neutral defects (dangling bonds), the light-induced metastable defects, the defects created by doping, and the singly occupied, localized band-tail states populated by light at low temperatures. The cross relaxation is only sensitive to the bulk spin density, and the surface spins have a negligible effect on the relaxation.




Phys. Rev. B 76, 172101 (2007)
1H and 31P nuclear magnetic resonance study of proton-irradiated KH2PO4
Se-Hun Kim,1,2 Kyu Won Lee,1 B. H. Oh,1 Cheol Eui Lee,1 and K. S. Hong3

Abstract:
We have studied the microscopic structure and dynamics in a proton-irradiated KH2PO4 single crystal. Our 1H and 31P nuclear magnetic resonance measurements indicate that proton irradiation gives rise to a decrease in the local dipolar order of the rigid lattice protons and an increase in interstitial protons as well as structural distortion of the PO4 tetrahedra.