Infrared absorption spectra of gaseous CH3OO detected with step-scan Fourier-transform infrared spectroscopy

• Main Authors: Hsu, Kuo-Hsiang, 徐國翔
• Other Authors: Lee, Yuan-Pern
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/85254926481666989391

碩士 === 國立交通大學 === 應用化學系分子科學碩博士班 === 101 === Abstract Methylperoxy (CH3OO), the simplest alkylperoxy radical, is an important intermediate in the oxidation of methane both in the atmosphere , and under combustion conditions . In this work, CH3OO radical were produced by irradiation of a flowing mixture of CH3I and O2 with KrF excimer laser at 248 nm. A step-scan time-resolved Fourier-transform spectrometer coupled with a multipath White cell was employed to record temporally resolved IR absorption spectra of reaction intermediate. Previously , transient absorption bands with origins at 3032.3, 2954.3, 1456.7, 1182.6, 1118.1, 3021.4, and 1440.9 cm－1 are assigned ν1-ν3, ν5-ν6, ν9 and ν10 modes of CH3OO, respectively. Recently, ν7 band is observed with origin at 910.7 cm－1. Besides, higher resolution spectra are obtained by irradiation of a flowing mixture of CH3C(O)CH3 and O2 with ArF excimer laser at 193 nm, so that rotational constants are available by using near prolate approximation model. The rotational contours of IR spectra of CH3OO, simulated based on ratios of predicted rotational parameters for the upper and lower states and on experimental rotational parameters of the ground state, agree satisfactorily with experimental results; the mixing ratios of a-, b-, and c-types of rotational structures were evaluated based on the direction of dipole derivatives predicted quantum chemically. Since the contribution of torsional splitting is non-negligible, we apply hot band transiton to simulate ν2 band. Though the result does not perfectly match, Q branch of ν2 band improves quite a lot.