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'Nuclear quadrupole resonance' in keywords Facet   section ZfN Section A  [X]
Facet   Publication Year 1998  [X]
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1Author    O. Ege, S. Nishijima, E. Kimura, H. Akiyama, S. Hamai, H. NegitaRequires cookie*
 Title    Powder Zeeman NQR Study on the Absorption Forms for Nuclear Spin 5/2  
 Abstract    For nuclei which have a nuclear spin of 5/2 and exhibit a small asymmetry parameter of the electric field gradient (77) at the nuclear site, line shapes of the Powder Zeeman NQR (PZNQR) spectra based on the transition between the energy levels m x = ± 1/2 and ± 3/2 (the lower frequency line) were stud-ied by means of computer simulations and experiments, (i) When an 77 value is very small (type 1; 77 = 0), the line shape exhibits two shoulders like the style of the American football player, (ii) While an 77 value is small (type 2; 0< 77 < around 0.01) but not zero, the line shape has two small peaks which are symmetrically located on the shoulders, as in the case of the small 77 type of spin 3/2. (iii) When an 77 value is not small (type 3; around 0.01 <77), the line shape has two symmetrical dips in stead of the peaks, which are also similar to the case of not small 77 type of spin 3/2. As the 77 value increases from around 0.01, the two dips grow and reach the maximum at the 77 value of 0.349, and then become small-er and obscure in the range of 77 larger than 0.349. __ The observations of PZNQR spectra were performed for several compounds including the ,27 I and/or 12 'Sb nuclei to estimate the 77 values, and gave the results as follows: very small for I (207.683 and 209.133 MHz, at 77 K) in Snl 4 ; very small for 127 I (176.496 and 177.438 MHz, at 77 K) in Gal 3 ; small for 127 I (265.102 MHz, at 77 K) in CH 3 I; 0.33 for 127 I (247.69 MHz, at 77 K) in C 2 H 5 I; 0.27 for 121 Sb (58.23 MHz, at 290 K) in SbCl 3 . The estimated 77 values were compared to those obtained from the fre-quencies of two NQR lines for spin 5/2. They were in good agreement with each other for the small re-gion of 77, though somewhat large disagreements were seen in the cases of not small 77 values. 
  Reference    Z. Naturforsch. 53a, 314—317 (1998); received March 24 1998 
  Published    1998 
  Keywords    NQR, Nuclear Quadrupole Resonance, Zeeman effect, Powder Zeeman NQR, Spin 5/2 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0314.pdf 
 Identifier    ZNA-1998-53a-0314 
 Volume    53 
2Author    Mariusz Maćkowiak, Piotr KątowskiRequires cookie*
 Title    2D Off-Resonance Nutation NQR Spectroscopy of Spin 3/2 Nuclei  
 Abstract    The effects of off-resonance irradiation in nutation NQR experiments are demonstrated both experimentally and theoretically. The theoretical description of the off-resonance effects in 2D nutation NQR spectroscopy is given, and general exact formulas for the asymmetry parameter are obtained. It is shown that the outcome of the off-resonance nutation experiments depends on the data acquisition procedure, leading to one-or three-line nutation spectra. To explain this fact and to describe the off-resonance nutation experiment properly, the transient response theory of a quadrupolar spin system to an RF pulse was modified using the wave-function approach. The 2D separation of interactions technique has been applied to separate a static and a randomly time-fluctuating dynamic part of the quadrupole interaction in the antiferroelectric phase of poly-crystalline ammonium dihydrogen arsenate. Two-dimensional off-resonance nutation NQR spectroscopy has been used to determine the full quadrupolar tensor of spin-3/2 nuclei in several molecular crystals containing the 35 C1 and 75 As nuclei. The off-resonance phenomena in 2D NQR are very important from the practical point of view (determination of r\ in multiple or broad-line spectrum) and also provide interesting information on the dynamic properties of a quadrupolar spin system. 
  Reference    Z. Naturforsch. 53a, 285—292 (1998); received January 26 1998 
  Published    1998 
  Keywords    Nuclear Quadrupole Resonance, 2D Nutation Spectroscopy, Off-resonance Irradiation, Electric Field Gradient Tensor 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0285.pdf 
 Identifier    ZNA-1998-53a-0285 
 Volume    53