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'81 Br NQR' in keywords Facet   Publication Year 1992  [X]
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1992[X]
1Author    G. K. Semin, A. M. Raevsky, S. I. Kuznetsov, T. L. Khotsyanova, S. I. GushchinRequires cookie*
 Title    Br NQR Spectra of the Impurity Molecules of Tetrabromides of Group IV Elements in the Matrix Crystals of Group IV Element Halides  
 Abstract    Changes in 79 Br NQR spectra of the impurity molecules EBr4 (2-5% mol) (E = C, Si, Ti, Ge, Sn) in the matrix crystals of group IV element tetrahalides EHal4 (E = Si. Ti, Ge, Sn; Hal = CI, Br) were studied at 77 K. The mixtures of these components are substitution solid solutions (SS), which was proved by the appearance of characteristic satellites in the NQR spectra of the matrix crystals. Changes in the Br NQR spectra of the impurity molecules were analyzed from the viewpoint of packing factors and the type of nearest environment. In the temperature range 77-270 K an abnormal temperature dependence of the 79 Br NQR frequencies of TiBr4 impurity in SiBr4 matrix was observed for both lines of the cubic phase. The temperature dependence of the 79 Br NQR frequencies of SiBr impurity in TiBr4 matrix is normal. 
  Reference    Z. Naturforsch. 47a, 111—116 (1992); received December 18 1991 
  Published    1992 
  Keywords    79, 81 Br NQR, Solid solutions, Group IV element tetrahalides, Temperature depen-dence of NQR frequencies 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0111.pdf 
 Identifier    ZNA-1992-47a-0111 
 Volume    47 
2Author    Hiromitsu Terao, Tsutomu Okuda, Aya Minami, Takashi Matsumoto, Yoshio TakedaRequires cookie*
 Title    Br and l27 I NQR Studies of (CH 3 NH 3 ) 2 HgBr 4 and (CH 3 NH 3 ) 2 HgI 4  
 Abstract    The 81 Br and 127 I NQR frequencies in (CH 3 NH 3) 2 HgBr 4 and (CH 3 NH 3) 2 HgI 4 , respectively, have been recorded from above 77 K to around room temperature. The resonance lines exist in a wide range of frequencies. An unusual temperature dependence of the resonance frequencies has been observed. Small 1 H-2 D isotope effects have been observed between (CH 3 ND 3) 2 HgBr 4 and (CH 3 NH 3) 2 HgBr 4 . Both negative and positive frequency differences between the deuterated and the nondeuterated compound have been observed at 77 K. The relatively large asymmetry parameters in the iodine compound decrease with increasing temperature, indicating the existence of H-bonds. The present results are interpreted qualitatively by considering the effects of H-bonding, N-H • • • X, between the halogen atoms and the CH 3 NH 3 ions which may undergo large molecular motions. It is suggested that not only frequency-lowering but also frequency-rising effects may be produced, depending on the direction of the H-bond, i.e., the angle between the Hg-X bond and the X • • • H bond. 
  Reference    Z. Naturforsch. 47a, 99—105 (1992); received October 8 1991 
  Published    1992 
  Keywords    81 Br NQR, 127 I NQR, Anomalous temperature dependence, r H-2 D isotope effect, H-bonding, Motions of CH 3 NH+ 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0099.pdf 
 Identifier    ZNA-1992-47a-0099 
 Volume    47