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Title
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Origin of abnormally sharp features in collision-induced spectra of cryosolutions
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Author
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Abstract
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| A weak, paradoxically narrow resonance feature (shortly, the r-line) near the O-2 fundamental frequency in the collision-induced absorption spectrum of oxygen dissolved in liquid argon and liquid nitrogen (T = 89 K) is resolved for the first time. An accurate band shape fitting routine to separate the r-line from the by-far more intense diffuse background and to study its behavior versus the oxygen mole fraction x which ranged from 0.03 up to 0.23 has been elaborated. At small x (less than or similar to 0.07), the r-line intensitywas found to scale as x(2) leaving no doubt that it is due to the solute-solute (O-2-O-2) interactions. In line with our results on the pH(2)-LNe cryosystem [Herrebout, Phys. Rev. Lett. 101, 093001 (2008)], the Lorentzian r-line shape and its extraordinary sharpness (half width at half height approximate to 1 cm(-1)) are indicative of the motional narrowing of the relative solute-solute translational spectrum. As x is further raised, ternary solute-solute interactions impede the r-line growth in the O-2-LAr spectrum because of the cancellation effect [J. Van Kranendonk, Physica 23, 825 (1957)]. Theoretical arguments are given that multiple interactions between the solutes should finally destroy the solute-solute induced r-line when the mixed solution approaches the limit of the pure liquid (x = 1). Interestingly, the nonbinary effects are too weak to appreciably affect the quadratic r-line scaling in the O-2-LN2 cryosystem which persists up to x = 0.23. It is emphasized that studies of the resonant features in the collision-induced spectra of binary cryosolutions open up unique opportunities to spectroscopically trace the microscopic-scale diffusion. (C) 2015 AIP Publishing LLC. |
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Language
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English
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Source (journal)
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The journal of chemical physics. - New York, N.Y.
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Publication
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New York, N.Y.
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2015
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ISSN
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0021-9606
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DOI
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10.1063/1.4927326
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Volume/pages
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143
:4
(2015)
, 10 p.
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Article Reference
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044508
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ISI
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000358929100052
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Pubmed ID
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26233146
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (open access)
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