Spectroscopic and calorimetric studies of proton tunneling and deuteration-induced phase transition in crystalline iodo-hydroxyphenalenone and iodo-deuteroxyphenalenone
Far-infrared spectra and molar heat capacities of 5-iodo-9-hydroxyphenalenone (IHP) and its deuterated analog (IDP) were measured at temperatures between 5 K and ambient temperature. A strong absorption at 68 cm −1 in IHP, for which the counterpart is missing in IDP, was assigned to the proton tunne...
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Published in | Chemical physics letters Vol. 342; no. 1; pp. 22 - 26 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Amsterdam
Elsevier B.V
06.07.2001
Elsevier Science |
Subjects | |
Online Access | Get full text |
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Summary: | Far-infrared spectra and molar heat capacities of 5-iodo-9-hydroxyphenalenone (IHP) and its deuterated analog (IDP) were measured at temperatures between 5 K and ambient temperature. A strong absorption at
68
cm
−1
in IHP, for which the counterpart is missing in IDP, was assigned to the proton tunneling. A heat capacity anomaly due to a phase transition occurred at 36.0 K in IDP with
Δ
trs
H=167
J
mol
−1
and
Δ
trs
S=5.45
J
K
−1
mol
−1
. No phase transition occurred in IHP, proving mutual exclusion of the tunneling and order–disorder transition. The results provide firm experimental evidence for discrete tunnel states in hydrogen-bonded crystals, the key concept in the theory of deuterium isotope effects in ferroelectricity. |
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ISSN: | 0009-2614 1873-4448 |
DOI: | 10.1016/S0009-2614(01)00560-7 |