【摘要】 利用同步辐射光源 ,结合飞行时间质谱 ,在超声射流冷却条件下研究了 (CH3 ) 2 NH(DMA)的光电离解离机理 .实验观察到四种主要离子 (CH3 ) 2 NH·+ ,CH3 NH+ CH2 ,CH2 NH2 + 和CHNH+ ,质荷比分别为m/z=45 ,44 ,30和 2 8.四种离子的出现势 (AE)分别为 8.2 6 ,9.5 2 ,11.93和 11.2 7eV ,其中分子电离势IP =(8.2 6± 0 .0 1)eV ,计算得到分子离子的生成热ΔfHo=778.5 5kJ/mol.分析表明离子CH3 NH+ CH2 来自母体离子的α去H过程 .其他碎片离子由后续逐级解离去H反应以及脱CH3 通道生成更多还原

【Abstract】 Photoionization and photodissociation of dimethylamine(DMA), by using synchrotron radiation combining with time of flight-mass spectroscopy(TOF-MS), is performed under supersonic molecular beam. Four main ions of (CH 3) 2NH· +, CH 3NH +CH 2, CH 2NH 2 + and CHNH + are observed, at appearance energy(AE) of 8.26, 9.52, 11.93 and 11.27 eV respectively. DMA’s IP=8.26 eV and heat of formation of parent ion Δ fH o=778.55 kJ/mol obtained are in well agreement with recommended values. The photo fragmentation mechanism is also discussed.更多还原