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Photolysis (193 nm) of SO2: nascent product energy distribution examined through IR emission


Ma, Jianqiang; Wilhelm, Michael J; Smith, Jonathan M; Dai, Hai-Lung (2012). Photolysis (193 nm) of SO2: nascent product energy distribution examined through IR emission. Journal of Physical Chemistry. A, 116(1):166-173.

Abstract

Infrared emission following the photolysis of SO(2) by a 193 nm laser pulse (20 ns duration) was recorded with 500 ns time and 10 cm(-1) spectral resolution. Spectral analyses of the time-resolved spectra revealed the vibrationally excited nascent SO population distribution as (v = 1)/(v = 2)/(v = 3)/(v = 4)/(v = 5) = 0.54 ± 0.04, 1.00 ± 0.03, 0.00 ± 0.03, 0.01 ± 0.03, and 0.10 ± 0.03. The nascent SO was found to be rotationally excited with an average rotational temperature around 1000 K for v = 1 and v = 2 levels and 300 K for the v = 5 level. The vibrationally excited SO likely originates from two distinct dissociation mechanisms; the v = 1 and 2 populations are generated through intersystem crossing between the C state and a repulsive state (2(3)A'), and the v = 5 population is generated through internal conversion from the C to the X state. Efficient V-V energy transfer from nascent vibrationally excited SO to SO(2)(ν(1)) is also observed. The appearance of the SO(2)(ν(1)) ν(1) = 2 emission, before that from the ν(1) = 1 population is consistent with the previous report that the Δν = -2 channel is more efficient than the Δν = -1 channel.

Abstract

Infrared emission following the photolysis of SO(2) by a 193 nm laser pulse (20 ns duration) was recorded with 500 ns time and 10 cm(-1) spectral resolution. Spectral analyses of the time-resolved spectra revealed the vibrationally excited nascent SO population distribution as (v = 1)/(v = 2)/(v = 3)/(v = 4)/(v = 5) = 0.54 ± 0.04, 1.00 ± 0.03, 0.00 ± 0.03, 0.01 ± 0.03, and 0.10 ± 0.03. The nascent SO was found to be rotationally excited with an average rotational temperature around 1000 K for v = 1 and v = 2 levels and 300 K for the v = 5 level. The vibrationally excited SO likely originates from two distinct dissociation mechanisms; the v = 1 and 2 populations are generated through intersystem crossing between the C state and a repulsive state (2(3)A'), and the v = 5 population is generated through internal conversion from the C to the X state. Efficient V-V energy transfer from nascent vibrationally excited SO to SO(2)(ν(1)) is also observed. The appearance of the SO(2)(ν(1)) ν(1) = 2 emission, before that from the ν(1) = 1 population is consistent with the previous report that the Δν = -2 channel is more efficient than the Δν = -1 channel.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Cardiovascular Surgery
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2012
Deposited On:15 Feb 2013 12:11
Last Modified:05 Apr 2016 16:27
Publisher:American Chemical Society
ISSN:1089-5639
Publisher DOI:https://doi.org/10.1021/jp2061943
PubMed ID:22148244

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