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'r H 2 D isotope effect' in keywords
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1992 (1)
1Author    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