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1998 (1)
1994 (1)
1Author    PascalP M AnRequires cookie*
 Title    Solomon Echoes Extended to Soft Pulse Excitation  
 Abstract    Solomon echoes, produced by two in-phase pulses separated by a delay r2, are derived in taking into account the first-order quadrupolar interaction during the pulses. Consequently, the results are valid for any ratio of the quadrupolar coupling, coQ, to the amplitude of the radiofrequency pulse, <yRF. Six echoes are predicted after the second pulse: three, detected as inner satellite signals, occur at t 4 = r2, t 4 = 2 t 2 and t 4 = 3 1 2; the other three, detected as outer satellite signals, occur at t 4 = r 2 /2, t 4 = t 2 , and t4 = 3 t 2 /2. These echoes originate from the refocusing of single-and multi-quantum off-resonance coherences developed during the first pulse. Four of them are allowed echoes, the other two are forbidden ones. However, there is no echo for the central transition. From a practical point of view this means that r2 must be short compared to TFID, the duration of the FID of the central transition. The behavior of the echo amplitude versus the second pulse length is discussed for several ratios of coQ/coRF. 
  Reference    Z. Naturforsch. 49a, 89 (1994); received July 23 1993 
  Published    1994 
  Keywords    Quadrupole effect, Spin-5/2, Spin echo NM R, Solomon echoes 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0089.pdf 
 Identifier    ZNA-1994-49a-0089 
 Volume    49 
2Author    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