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1998 (2)
1Author    David Stephenson, JohnA S Smith, St Augustine, Tobago TrinidadRequires cookie*
 Title    Double Resonance Detection Using Zero Field Level Crossing  
 Abstract    Double resonance level crossing detection cannot normally be used to record transitions between the quadrupole Zeeman levels. Neither can it be used if the quadrupole resonance frequency is larger than the proton NMR frequency in high field. A simple variation of the level crossing experiment is demonstrated which allows energy to be efficiently transferred from quadrupole to proton system and hence lead to detection in these two cases. In the case of the quadrupole Zeeman levels it allows transitions between the ±\ levels to be detected in a small magnetic field, allowing measurement of the asymmetry parameter (r\) for spin 3/2 systems. This is demonstrated for the 1X B nucleus in triethanolamine borate. Detection of high frequency quadrupole transitions is demonstrated from which relaxation information is obtained. 
  Reference    Z. Naturforsch. 53a, 301—304 (1998); received October 31 1997 
  Published    1998 
  Keywords    NQR, Asymmetry Parameter, Relaxation, n B, 35 C1 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0301.pdf 
 Identifier    ZNA-1998-53a-0301 
 Volume    53 
2Author    H. Yoshida, H. Nishihara, S. Yokota, M. Ohyanagi, T. NakaokiRequires cookie*
 Title    Field-Swept NMR Spectra of n B in Pyrex Glass and 93 Nb in NbN Perturbed by Quadrupole Interaction  
 Abstract    NMR experiments of "B by both field-swept and high-resolution NMR are reported to probe the electric field gradient at boron sites and its distribution in Pyrex glass. Both spectra are successfully interpreted with the same set of parameters. It is stressed that field-swept NMR experiments to observe total powder spectrum can be helpful to get information on electric field gradients and asymmetry pa-rameters if there exist many nonequivalent sites of atoms, since satellite transitions are affected by the larger first-order quadrupole effect. Field-swept NMR of 93 Nb in superconducting NbN powder, pre-pared by self-propagating high-temperature synthesis, is also reported. A very broad field-swept spec-trum disturbed by quadrupole interaction has been observed. The spectrum is simulated by assuming distributions in electric field gradient and Knight shift at Nb sites. It is stressed that a combination of experiments at separated frequencies is important 
  Reference    Z. Naturforsch. 53a, 309—313 (1998); received January 26 1998 
  Published    1998 
  Keywords    NMR, Pyrex, Glass, n B, NbN, Superconductor, 93 Nb 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0309.pdf 
 Identifier    ZNA-1998-53a-0309 
 Volume    53