Isotopically selective IR multiphoton dissociation of 1,3,5-trioxane |
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Authors: | V Churakov W Fuss |
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Institution: | (1) Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany;(2) Present address: Institut Fiziki Belarussk. Akad. Nauk pr., Skorina, 220602 Minsk, Belarus |
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Abstract: | Searching for oxygen-isotope selectivity, we investigated the infrared multiphoton dissociation of the formaldehyde trimer around 10 µm, in a range where the molecule has a degenerate and a non-degenerate CO stretch vibration and a degenerate CH2 deformation vibration. In the region of the two latter, the wavelength dependence of the dissociation yield exhibits sharp structures. They were assigned ton-photon resonances (n = 2, 3, 5) by the help of the IR spectrum in the fundamental and overtone region. The O and C selectivities were very small (1.05) near the non-degenerate CO stretch band, but surprisingly large (2–4) in the CH2 deformation, which has no isotopic shift. The selectivity is not controlled by the first (n-photon) excitation step, but only by a later step. Its assignment is attempted. The pressure dependence of the dissociation is peculiar: Only after an initial decrease, the yield exhibits the usual rise with pressure. We attribute the decrease to a relaxation which perturbs the two-photon resonance. |
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Keywords: | 33 80 Wz |
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