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Title: Interrogating the vibrational relaxation of highly excited polyatomics with time-resolved diode laser spectroscopy: C sub 6 H sub 6 , C sub 6 D sub 6 , and C sub 6 F sub 6 +CO sub 2

Abstract

The vibrational relaxation of highly excited ground state benzene, benzene {ital d}{sub 6}, and hexafluorobenzene by CO{sub 2} has been investigated with high resolution diode laser spectroscopy. The vibrationally hot polyatomics are formed by single photon 248 nm excitation to the S{sub 1} state followed by rapid radiationless transitions. It has been found that in all cases less than 1% of the energy initially present in the polyatomics is deposited into the high frequency mode of CO{sub 2} ({nu}{sub 3}). An investigation of the CO{sub 2}(00{sup 0}1) nascent rotational distribution under single collision conditions reveals that very little rotational excitation accompanies vibrational energy transfer to the {nu}{sub 3} mode. The CO{sub 2}({nu}{sub 3}) rotational states can be described by temperatures, {ital T}{sub rot}, as follows: C{sub 6}H{sub 6}, {ital T}{sub rot} =360{plus minus}30 K; C{sub 6}D{sub 6}, {ital T}{sub rot} =350{plus minus}35 K and C{sub 6}F{sub 6}, {ital T}{sub rot} =340{plus minus}23 K. An estimate of {l angle}{Delta}{ital E}{r angle}{sub {nu}3}, the mean energy transferred to the CO{sub 2} {nu}{sub 3} mode per collision, suggests that as the availability of low frequency modes in the excited molecule increases, less energy is deposited into the high frequency mode of CO{sub 2}.more » Finally, evidence is presented suggesting that even at moderate laser fluences, the two-photon ionization of benzene can lead to substantial CO{sub 2} {nu}{sub 3} excitation via electron+CO{sub 2} inelastic collisions.« less

Authors:
;  [1];  [2]
  1. (Brookhaven National Laboratory, Department of Chemistry, Upton, New York 11973 (USA))
  2. (Department of Chemistry and Columbia Radiation Laboratory, Columbia University, New York, New York 10027 (USA))
Publication Date:
OSTI Identifier:
5539773
DOE Contract Number:  
AC02-76CH00016; FG02-88ER13937
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics; (USA)
Additional Journal Information:
Journal Volume: 94:10; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BENZENE; MOLECULE-MOLECULE COLLISIONS; RELAXATION; CARBON DIOXIDE; FLUORINATED AROMATIC HYDROCARBONS; DEUTERIUM COMPOUNDS; ENERGY TRANSFER; EXCITATION; EXCITED STATES; LASER SPECTROSCOPY; PHOTOCHEMISTRY; POLYATOMIC MOLECULES; ULTRAVIOLET RADIATION; VIBRATIONAL STATES; AROMATICS; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; CHEMISTRY; COLLISIONS; ELECTROMAGNETIC RADIATION; ENERGY LEVELS; ENERGY-LEVEL TRANSITIONS; HALOGENATED AROMATIC HYDROCARBONS; HYDROCARBONS; HYDROGEN COMPOUNDS; MOLECULE COLLISIONS; MOLECULES; ORGANIC COMPOUNDS; ORGANIC FLUORINE COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; RADIATIONS; SPECTROSCOPY; 640302* - Atomic, Molecular & Chemical Physics- Atomic & Molecular Properties & Theory; 400102 - Chemical & Spectral Procedures

Citation Formats

Sedlacek, A.J., Weston, R.E. Jr., and Flynn, G.W. Interrogating the vibrational relaxation of highly excited polyatomics with time-resolved diode laser spectroscopy: C sub 6 H sub 6 , C sub 6 D sub 6 , and C sub 6 F sub 6 +CO sub 2. United States: N. p., 1991. Web. doi:10.1063/1.460277.
Sedlacek, A.J., Weston, R.E. Jr., & Flynn, G.W. Interrogating the vibrational relaxation of highly excited polyatomics with time-resolved diode laser spectroscopy: C sub 6 H sub 6 , C sub 6 D sub 6 , and C sub 6 F sub 6 +CO sub 2. United States. doi:10.1063/1.460277.
Sedlacek, A.J., Weston, R.E. Jr., and Flynn, G.W. Wed . "Interrogating the vibrational relaxation of highly excited polyatomics with time-resolved diode laser spectroscopy: C sub 6 H sub 6 , C sub 6 D sub 6 , and C sub 6 F sub 6 +CO sub 2". United States. doi:10.1063/1.460277.
@article{osti_5539773,
title = {Interrogating the vibrational relaxation of highly excited polyatomics with time-resolved diode laser spectroscopy: C sub 6 H sub 6 , C sub 6 D sub 6 , and C sub 6 F sub 6 +CO sub 2},
author = {Sedlacek, A.J. and Weston, R.E. Jr. and Flynn, G.W.},
abstractNote = {The vibrational relaxation of highly excited ground state benzene, benzene {ital d}{sub 6}, and hexafluorobenzene by CO{sub 2} has been investigated with high resolution diode laser spectroscopy. The vibrationally hot polyatomics are formed by single photon 248 nm excitation to the S{sub 1} state followed by rapid radiationless transitions. It has been found that in all cases less than 1% of the energy initially present in the polyatomics is deposited into the high frequency mode of CO{sub 2} ({nu}{sub 3}). An investigation of the CO{sub 2}(00{sup 0}1) nascent rotational distribution under single collision conditions reveals that very little rotational excitation accompanies vibrational energy transfer to the {nu}{sub 3} mode. The CO{sub 2}({nu}{sub 3}) rotational states can be described by temperatures, {ital T}{sub rot}, as follows: C{sub 6}H{sub 6}, {ital T}{sub rot} =360{plus minus}30 K; C{sub 6}D{sub 6}, {ital T}{sub rot} =350{plus minus}35 K and C{sub 6}F{sub 6}, {ital T}{sub rot} =340{plus minus}23 K. An estimate of {l angle}{Delta}{ital E}{r angle}{sub {nu}3}, the mean energy transferred to the CO{sub 2} {nu}{sub 3} mode per collision, suggests that as the availability of low frequency modes in the excited molecule increases, less energy is deposited into the high frequency mode of CO{sub 2}. Finally, evidence is presented suggesting that even at moderate laser fluences, the two-photon ionization of benzene can lead to substantial CO{sub 2} {nu}{sub 3} excitation via electron+CO{sub 2} inelastic collisions.},
doi = {10.1063/1.460277},
journal = {Journal of Chemical Physics; (USA)},
issn = {0021-9606},
number = ,
volume = 94:10,
place = {United States},
year = {1991},
month = {5}
}