PHOTOABSORPTION, PHOTOIONIZATION, AND NEUTRAL DISSOCIATION CROSS-SECTIONS OF DIMETHYL ETHER AND ETHYL METHYL-ETHER IN THE EXTREME-ULTRAVIOLET RANGE

被引:15
作者
KAMETA, K [1 ]
UKAI, M [1 ]
KAMOSAKI, T [1 ]
SHINSAKA, K [1 ]
KOUCHI, N [1 ]
HATANO, Y [1 ]
TANAKA, K [1 ]
机构
[1] NATL LAB HIGH ENERGY PHYS,PHOTON FACTORY,OHO,IBARAKI 305,JAPAN
关键词
D O I
10.1063/1.462781
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The absolute photoionization and neutral dissociation cross sections of dimethyl ether (CH3OCH3) and ethyl methyl ether (CH3CH2OCH3) in the 52-92 nm range have been obtained by measuring the absolute photoabsorption cross sections and photoionization quantum yields using a multistage ionization chamber and synchrotron radiation. A large deviation in the photionization quantum yield of both molecules from unity, namely a noticeable enhancement of the neutral fragmentation cross sections, has shown that superexcited states exist densely in this wavelength range. Fluorescence excitation spectra of neutral dissociation fragments produced in the 35-100 nm photon impact on both molecules have also been measured by observing ultraviolet and vacuum ultraviolet emissions. A general appearance of the neutral dissociation cross section correlates with the fluorescence excitation spectra from H (n = 2), CH (A (2)DELTA), and CH3O(A approximately). The superexcited states of dimethyl ether observed are shown to be purely repulsive states or bound states for which the lowest energy level achieved from the Franck-Condon region is higher than the dissociation limit. Dissociation of ionic satellites have also been observed in the fluorescence excitation spectra of both molecules.
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页码:4911 / 4917
页数:7
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