用飞行时间质谱技术研究丙酮的多光子电离

基于飞行时间质谱(TOF)研究了丙酮分子3p里德堡态光谱和丙酮离子的光解离.在320-337nm激光波长范围内,采用线极化双光子共振增强多光子电离技术研究丙酮分子3p里德堡态的的光谱,观察到了新的跃迁谱带.除母体CH3COCH3+离子之外,同时观察到了碎片离子CH3CO+和CH3+.由CH3COCH3+、CH3CO+和CH3+离子信号强度与激光能量的依赖关系导出这些离子产生的光子级数,分别为三光子、四光子、四光子过程.CH3CO+和CH3+是由基态的CH3COCH3+离子再吸收一个光子后裂解产生的.对CH3COCH+3(X)+1.hv→CH3CO++CH3和CH3COCH3+(X)+1.hv→CH3++CH3CO解离通道,分别由CH3CO+和CH3+离子TOF峰形获得了这两个解离通道的平均平动能释放.

A Multiphoton Ioniation Study of Acetone Using Time-of-Flight Mass Spectromentry

Spectroscopy of 3p Rydberg states of acetone and photodissociation of acetone cation are studied using time-of-flight(TOF) mass spectrometry.The 3p Rydberg state spectroscopy of acetone is investigated with linearly polarized 2-photon resonance enhanced multiphoton ionization(REMPI) in the wavelength range of 320-337nm,resulting in the observation of several new transition bands.In addition to the CH3COCH+3 ion,CH3CO+ and CH+3 fragments are observed.The laser power dependences suggest that the CH3COCH+3,CH3CO+ and CH+3 ions are produced in 3-,4-,and 4-photon processes,respectively.Production of CH3CO+ and CH+3 involve excitation of the ground state acetone cation by an additional photon and subsequent decomposition of the excited acetone ion.The average translational energy of CH3CO+ and CH+3 from dissociation in CH3COCH+3(X)+1·hv→CH3CO++CH3 and CH3COCH+3(X)+1·hv→CH+3+CH3CO are derived from the ion TOF peak profiles.