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Title: Matrix-isolated infrared absorption spectrum of CH 2 BrOO radical

Authors:
; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1326440
Grant/Contract Number:
FG02-07ER15884; F-1284
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Chemical Physics Letters
Additional Journal Information:
Journal Volume: 657; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-03 21:02:23; Journal ID: ISSN 0009-2614
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Zhang, Xu, Sander, Stanley P., Cheng, Lan, Thimmakondu, Venkatesan S., and Stanton, John F. Matrix-isolated infrared absorption spectrum of CH 2 BrOO radical. Netherlands: N. p., 2016. Web. doi:10.1016/j.cplett.2016.05.060.
Zhang, Xu, Sander, Stanley P., Cheng, Lan, Thimmakondu, Venkatesan S., & Stanton, John F. Matrix-isolated infrared absorption spectrum of CH 2 BrOO radical. Netherlands. doi:10.1016/j.cplett.2016.05.060.
Zhang, Xu, Sander, Stanley P., Cheng, Lan, Thimmakondu, Venkatesan S., and Stanton, John F. Fri . "Matrix-isolated infrared absorption spectrum of CH 2 BrOO radical". Netherlands. doi:10.1016/j.cplett.2016.05.060.
@article{osti_1326440,
title = {Matrix-isolated infrared absorption spectrum of CH 2 BrOO radical},
author = {Zhang, Xu and Sander, Stanley P. and Cheng, Lan and Thimmakondu, Venkatesan S. and Stanton, John F.},
abstractNote = {},
doi = {10.1016/j.cplett.2016.05.060},
journal = {Chemical Physics Letters},
number = C,
volume = 657,
place = {Netherlands},
year = {Fri Jul 01 00:00:00 EDT 2016},
month = {Fri Jul 01 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.cplett.2016.05.060

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  • Matrix photoionization and radiolysis of methylene chloride and bromide produced and isolated the CH/sub 2/X/sub 2//sup +/ and CHX/sub 2//sup +/ ions for spectroscopic and photochemical study. The antisymmetric vibrations observed for the parent ions show unusual isotope shifts, which are explained by spin-orbit interaction of the lowest two electronic states of CH/sub 2/X/sub 2//sup +/ formed by removal of halogen nonbonding electrons. The major ultraviolet absorption to an excited electronic state of each ion nicely correlates with photoelectron spectra. The parent ions photodissociated with red-visible light, which is in accord with their limited stability in the gas phase. Ultravioletmore » photolysis of these matrix samples produced infrared spectra of the isolated CHX/sub 2//sup +/ ions, CHX/sub 2/ radicals, and the matrix solvated proton Ar/sub n/H/sup +/. 4 figures, 7 tables.« less
  • We report the infrared absorption spectrum of the methylthio (or thiomethoxy) radical, CH{sub 3}S (X {sup 2}E{sub 3/2}), produced via photodissociation in situ of three precursors CH{sub 3}SH, CH{sub 3}SCH{sub 3}, and CH{sub 3}SSCH{sub 3} isolated in solid p-H{sub 2}. The common absorption features observed with similar intensity ratios in each experiment are assigned to CH{sub 3}S. The wavenumbers of these features agree satisfactorily with those predicted with a spin-vibronic Hamiltonian accounting for the anharmonic effects and the Jahn-Teller effects to the quartic term [A. V. Marenich and J. E. Boggs, J. Chem. Theory Comput. 1, 1162 (2005)]. In additionmore » to an absorption line at 724.2 cm{sup -1}, corresponding to a transition of 3{sup 1} previously determined to be 727 cm{sup -1} from fluorescence spectra of gaseous CH{sub 3}S, we identified fundamental transitions 6{sup 1}(a{sub 1}) at 771.1, 6{sup 1}(e) at 1056.6, 5{sup 1}(a{sub 1}) at 1400.0, 4{sup 1}(a{sub 1}) at 2898.4 cm{sup -1}, and several combination and overtone transitions. In contrast, photolysis of CH{sub 3}SSCH{sub 3} isolated in solid Ar produces mainly H{sub 2}CS, CH{sub 3}SH, and CS{sub 2}, but no CH{sub 3}S. These results demonstrate the feasibility of using photolysis in situ of precursors isolated in solid p-H{sub 2} to produce free radicals by taking advantage of the diminished cage effect of the matrix.« less
  • We have recorded infrared spectra of acetyl radical (CH{sub 3}CO) and CH{sub 3}-CO complex in solid para-hydrogen (p-H{sub 2}). Upon irradiation at 248 nm of CH{sub 3}C(O)Cl/p-H{sub 2} matrices, CH{sub 3}CO was identified as the major product; characteristic intense IR absorption features at 2990.3 (ν{sub 9}), 2989.1 (ν{sub 1}), 2915.6 (ν{sub 2}), 1880.5 (ν{sub 3}), 1419.9 (ν{sub 10}), 1323.2 (ν{sub 5}), 836.6 (ν{sub 7}), and 468.1 (ν{sub 8}) cm{sup −1} were observed. When CD{sub 3}C(O)Cl was used, lines of CD{sub 3}CO at 2246.2 (ν{sub 9}), 2244.0 (ν{sub 1}), 1866.1 (ν{sub 3}), 1046.7 (ν{sub 5}), 1029.7 (ν{sub 4}), 1027.5 (ν{sub 10}),more » 889.1 (ν{sub 6}), and 723.8 (ν{sub 7}) cm{sup −1} appeared. Previous studies characterized only three vibrational modes of CH{sub 3}CO and one mode of CD{sub 3}CO in solid Ar. In contrast, upon photolysis of a CH{sub 3}I/CO/p-H{sub 2} matrix with light at 248 nm and subsequent annealing at 5.1 K before re-cooling to 3.2 K, the CH{sub 3}-CO complex was observed with characteristic IR features at 3165.7, 3164.5, 2150.1, 1397.6, 1396.4, and 613.0 cm{sup −1}. The assignments are based on photolytic behavior, observed deuterium isotopic shifts, and a comparison of observed vibrational wavenumbers and relative IR intensities with those predicted with quantum-chemical calculations. This work clearly indicates that CH{sub 3}CO can be readily produced from photolysis of CH{sub 3}C(O)Cl because of the diminished cage effect in solid p-H{sub 2} but not from the reaction of CH{sub 3} + CO because of the reaction barrier. Even though CH{sub 3} has nascent kinetic energy greater than 87 kJ mol{sup −1} and internal energy ∼42 kJ mol{sup −1} upon photodissociation of CH{sub 3}I at 248 nm, its energy was rapidly quenched so that it was unable to overcome the barrier height of ∼27 kJ mol{sup −1} for the formation of CH{sub 3}CO from the CH{sub 3} + CO reaction; a barrierless channel for formation of a CH{sub 3}-CO complex was observed instead. This rapid quenching poses a limitation in production of free radicals via bimolecular reactions in p-H{sub 2}.« less
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