在含有 CH3I 和 SO2 的 p-H2 基质中辐照时观察到的 CH3SO2 的红外吸收。

Infrared absorption of CH3SO2 observed upon irradiation of a p-H2 matrix containing CH3I and SO2.

机构信息

Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan.

出版信息

J Chem Phys. 2011 Mar 28;134(12):124314. doi: 10.1063/1.3567117.

DOI:10.1063/1.3567117

PMID:21456669

Abstract

Irradiation with a mercury lamp at 254 nm of a p-H(2) matrix containing CH(3)I and SO(2) at 3.3 K, followed by annealing of the matrix, produced prominent features at 633.8, 917.5, 1071.1 (1072.2), 1272.5 (1273.0, 1273.6), and 1416.0 cm(-1), attributable to ν(11) (C-S stretching), ν(10) (CH(3) wagging), ν(8) (SO(2) symmetric stretching), ν(7) (SO(2) antisymmetric stretching), and ν(4) (CH(2) scissoring) modes of methylsulfonyl radical (CH(3)SO(2)), respectively; lines listed in parentheses are weaker lines likely associated with species in a different matrix environment. Further irradiation at 365 nm diminishes these features and produced SO(2) and CH(3). Additional features at 1150.1 and 1353.1 (1352.7) cm(-1) are tentatively assigned to the SO(2) symmetric and antisymmetric stretching modes of ISO(2). These assignments are based on comparison of observed vibrational wavenumbers and (18)O- and (34)S-isotopic shifts with those predicted with the B3P86 method. Our results agree with the previous report of transient IR absorption bands of gaseous CH(3)SO(2) at 1280 and 1076 cm(-1). These results demonstrate that the cage effect of solid p-H(2) is diminished so that CH(3) radicals, produced via UV photodissociation of CH(3)I in situ, might react with SO(2) to form CH(3)SO(2) during irradiation and upon annealing. Observation of CH(3)SO(2) but not CH(3)OSO is consistent with the theoretical predictions that only the former reactions proceed via a barrierless path.

摘要

用 254nm 的汞灯对含有 CH3I 和 SO2 的 p-H2 基质进行辐照，在 3.3K 下，然后对基质进行退火，在 633.8、917.5、1071.1（1072.2）、1272.5（1273.0、1273.6）和 1416.0cm-1 处产生了明显的特征，归因于甲基磺酰基自由基（CH3SO2）的 ν（11）（C-S 伸缩）、ν（10）（CH3 摇摆）、ν（8）（SO2 对称伸缩）、ν（7）（SO2 反对称伸缩）和 ν（4）（CH2 剪断）模式；括号中列出的谱线是可能与不同基质环境中的物质相关的较弱谱线。进一步用 365nm 光辐照会减弱这些特征，并产生 SO2 和 CH3。在 1150.1 和 1353.1（1352.7）cm-1 处的附加特征被暂时分配给 ISO2 的 SO2 对称和反对称伸缩模式。这些分配是基于与用 B3P86 方法预测的观察到的振动波数和（18）O 和（34）S 同位素位移的比较。我们的结果与先前关于气态 CH3SO2 在 1280 和 1076cm-1 处的瞬态红外吸收带的报告一致。这些结果表明，固态 p-H2 的笼效应减弱，因此，通过 CH3I 的 UV 光解原位产生的 CH3 自由基可能在辐照和退火过程中与 SO2 反应生成 CH3SO2。只观察到 CH3SO2 而不是 CH3OSO，这与仅前一种反应通过无势垒途径进行的理论预测一致。