Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.

The photodissociation dynamics of CH2I2 has been studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(2P3/2) and spin-orbit excited state I*(2P1/2) iodine atoms, which are produced from photodissociation of CH2I2 at this wavelength. These processes are found to occur via B1 ← A1 type electronic transitions. The quantum yield of I*(2P1/2) is determined to be 0.25, indicating that the formation of ground state iodine is clearly the favored dissociation channel in the 304 nm wavelength region. From the angular distribution of dissociation products, the anisotropy parameters are determined to be β (I)=0.4 for the I(2P3/2) and β(I*)=0.55 for the I*(2P1/2) which substantially differ from the limiting value of 1.13. The positive values of anisotropy parameter, however, show that the primary processes for I and I* formation channels proceed dominantly via a transition which is parallel to I-I axis. The above results are interpreted in terms of dual path formation of iodine atoms from two different excited states, i.e., a direct and an indirect dissociation via curve crossing between these states. The translational energy distributions of recoil fragments reveal that a large fraction of the available energy goes into the internal excitation of the CH2I photofragment; < Eint > /Eavl=0.80 and 0.82 for the I and I* formation channels, respectively. The quantitative analysis for the energy partitioning of available energy into the photofragments is used to compare the experimental results with the prediction of direct impulsive model for photodissociation dynamics.

Main Author: Jung, Kwang-Woo.
Other Authors: Ahmadi, Temer S., El-Sayed, Mostafa A.
Format: Villanova Faculty Authorship
Language: English
Published: 1997
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dc_source_str_mv Bulletin of the Korean Chemical Society, 18(12), December 20, 1997, 1274-1280.
author Jung, Kwang-Woo.
author_facet_str_mv Jung, Kwang-Woo.
Ahmadi, Temer S.
El-Sayed, Mostafa A.
author_or_contributor_facet_str_mv Jung, Kwang-Woo.
Ahmadi, Temer S.
El-Sayed, Mostafa A.
author_s Jung, Kwang-Woo.
spellingShingle Jung, Kwang-Woo.
Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
author-letter Jung, Kwang-Woo.
author_sort_str Jung, Kwang-Woo.
author2 Ahmadi, Temer S.
El-Sayed, Mostafa A.
author2Str Ahmadi, Temer S.
El-Sayed, Mostafa A.
dc_title_str Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
title Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
title_short Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
title_full Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
title_fullStr Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
title_full_unstemmed Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
collection_title_sort_str photofragmentation translational spectroscopy of ch2i2 at 304nm: polarization dependence and energy partitioning.
title_sort photofragmentation translational spectroscopy of ch2i2 at 304nm: polarization dependence and energy partitioning.
format Villanova Faculty Authorship
description The photodissociation dynamics of CH2I2 has been studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(2P3/2) and spin-orbit excited state I*(2P1/2) iodine atoms, which are produced from photodissociation of CH2I2 at this wavelength. These processes are found to occur via B1 ← A1 type electronic transitions. The quantum yield of I*(2P1/2) is determined to be 0.25, indicating that the formation of ground state iodine is clearly the favored dissociation channel in the 304 nm wavelength region. From the angular distribution of dissociation products, the anisotropy parameters are determined to be β (I)=0.4 for the I(2P3/2) and β(I*)=0.55 for the I*(2P1/2) which substantially differ from the limiting value of 1.13. The positive values of anisotropy parameter, however, show that the primary processes for I and I* formation channels proceed dominantly via a transition which is parallel to I-I axis. The above results are interpreted in terms of dual path formation of iodine atoms from two different excited states, i.e., a direct and an indirect dissociation via curve crossing between these states. The translational energy distributions of recoil fragments reveal that a large fraction of the available energy goes into the internal excitation of the CH2I photofragment; < Eint > /Eavl=0.80 and 0.82 for the I and I* formation channels, respectively. The quantitative analysis for the energy partitioning of available energy into the photofragments is used to compare the experimental results with the prediction of direct impulsive model for photodissociation dynamics.
publishDate 1997
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fgs.label Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
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dc.title Photofragmentation Translational Spectroscopy of CH2I2 at 304nm: Polarization Dependence and Energy Partitioning.
dc.creator Jung, Kwang-Woo.
Ahmadi, Temer S.
El-Sayed, Mostafa A.
dc.description The photodissociation dynamics of CH2I2 has been studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(2P3/2) and spin-orbit excited state I*(2P1/2) iodine atoms, which are produced from photodissociation of CH2I2 at this wavelength. These processes are found to occur via B1 ← A1 type electronic transitions. The quantum yield of I*(2P1/2) is determined to be 0.25, indicating that the formation of ground state iodine is clearly the favored dissociation channel in the 304 nm wavelength region. From the angular distribution of dissociation products, the anisotropy parameters are determined to be β (I)=0.4 for the I(2P3/2) and β(I*)=0.55 for the I*(2P1/2) which substantially differ from the limiting value of 1.13. The positive values of anisotropy parameter, however, show that the primary processes for I and I* formation channels proceed dominantly via a transition which is parallel to I-I axis. The above results are interpreted in terms of dual path formation of iodine atoms from two different excited states, i.e., a direct and an indirect dissociation via curve crossing between these states. The translational energy distributions of recoil fragments reveal that a large fraction of the available energy goes into the internal excitation of the CH2I photofragment; < Eint > /Eavl=0.80 and 0.82 for the I and I* formation channels, respectively. The quantitative analysis for the energy partitioning of available energy into the photofragments is used to compare the experimental results with the prediction of direct impulsive model for photodissociation dynamics.
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