乙酰基的电子激发态

A Study of Excited States of Acetyl Radical

对乙酰基的基态（X12A′）和激发态进行了理论和实验研究。通过采用MRSDCI和MP2方法计算，获得了CH3CO自由基的四个电子激发态（A12A″，B22A′，C32A′，D22A″），其垂直激发能分别为250．8kJ·mol－1，472．3kJ·mol－1，645．8kJ·mol－1和674．7kJ·mol－1。运用时间分辨付里叶红外光谱仪（TR－FTIR）分别研究了CH3CO自由基的热解和光解反应，观察到初生产物CO（V）的红外发射光谱．势垒仅为75．2kJ·mol－1的基态CH3CO极易热解．532um的激光只能将CH3CO激发到束缚态A12A″，故未观察到CO信号；而248nm或266nm的激光可使CH3CO发生B22A′←X12A′跃迁，生成高振动激发的CO（V8）产物．

Excited states of the acetyl radical (CH3CO) have been studied by means of theoretical and experimental methods. The four low-lying excited states (A 12A″, B 22A′, C 3'A′, and D 22A″) and their vertical excitation energies have been calculated at the MPZ and MRSDCI levels.Thermal decomposition of the ground state of CH3CO and photodissociation of the first and second states (A 12A″ and B 2'A′) have been investigated by Time-Resolved Fourier Transform Infrared Emission Spectroscopy. Vibrational products CO(ν) have been observed. The first electronically excited state (A 12A″) of CH3CO is a bound state, and the second electronically excited state (B22A′) of CH3CO is a predissociation state.