Dissociation of methanol in intense femtosecond laser field  

作　　者：Xiaoping Tang Lirong Gao Yonglin Wang Cao Wang Sufan Wang Fan’ao Kong 

机构地区：[1]Chinese Acad Sci, Inst Chem, Beijing 100080, Peoples R China

出　　处：《Chinese Science Bulletin》2002年第23期1973-1978,共6页

基　　金：This work was supported by the National Natural Science Foundation of China (Grant No. 29973052) ;the Ministry of Science & Technology of China.

摘　　要：Methanol was irradiated by 80 fs laser pulse, intensity range of 1013-1014 W/cm2. A TOF-mass spectrometer was coupled to the laser system and used to detect the ions produced. The parent ions CH3OH+ appeared firstly at the laser intensity of 1.4 ×1013 W/cm2. While the laser intensity was gradually increased, the parent ions were dissociated and the primary ions CH2OH+ were given as verified from the irradiation of deuterated methanol (CH3OD) showing the C-H bond cracking firstly. While the laser intensity was further increased to 2.0 ×1013 W/cm2, the C-O bonds of the parent ions also broke to give CH3+. When the laser intensity was higher, smaller fragment ions like CH+, C+, OH+ and O+ also appeared. Among the fragment ions, only H+ ion yield had anisotropic angular distribution dependence on the laser polarization vector in the dissociation of methanol. All the experimental observations show that the dissociation of methanol proceeds through stepwise mechanism but not Coulomb explosion.Methanol was irradiated by 80 fs laser pulse, intensity range of 1013–1014 W/cm2. A TOF-mass spectrometer was coupled to the laser system and used to detect the ions produced. The parent ions CH3OH+ appeared firstly at the laser intensity of 1.4×1013 W/cm2. While the laser intensity was gradually increased, the parent ions were dissociated and the primary ions CH2OH+ were given as verified from the irradiation of deuterated methanol (CH3OD) showing the C—H bond cracking firstly. While the laser intensity was further increased to 2.0 × 1013 W/cm2, the C—O bonds of the parent ions also broke to give CH3 +. When the laser intensity was higher, smaller fragment ions like CH+, C+, OH+ and O+ also appeared. Among the fragment ions, only H+ ion yield had anisotropic angular distribution dependence on the laser polarization vector in the dissociation of methanol. All the experimental observations show that the dissociation of methanol proceeds through stepwise mechanism but not Coulomb explosion.

关 键 词：INTENSE LASER field FEMTOSECOND LASER DISSOCIATION METHANOL TOF-mass spectra. 

分 类 号：O621[理学—有机化学]