离子速度影像法研究n-C_7H_(15)Br分子光解反应动力学  

Photodissociation Dynamics of n-C_7H_(15)Br Molecule by Ion Velocity Imaging

作　　者：渠洪波[1] 梁峰[2,3] 魏政荣[4] 李海洋[2] 张冰[4] 

机构地区：[1]中国科学院安徽光学精密机械研究所 [2]中国科学院武汉物理与数学研究所,波谱与原子分子物理国家重点实验室 [3]中国科学院大连化学物理研究所 [4]中国科学院研究生院,北京100049

出　　处：《物理化学学报》2006年第9期1106-1110,共5页Acta Physico-Chimica Sinica

基　　金：中国科学院创新基金资助项目

摘　　要：利用离子速度成像方法,研究n-C7H15Br分子在231～239nm范围内几个波长处的光解离动力学.通过同一束激光经(2+1)共振多光子电离(REMPI)过程探测光解碎片Br(2P3/2)和Br*(2P1/2),得到了不同激光波长处的离子速度分布图像,从而获得C7H15Br光解产物的能量分配和角度分布.结合各向异性参数和量子产率,计算了n-C7H15Br分子在234nm波长下不同解离通道的比例.实验表明光解产物的能量分配可以用冲击模型中的软碰撞模型来解释.实验还发现,各向异性参数!(Br*)的值对光波长变化很敏感,这是由电子激发态的绝热和非绝热过程决定的.Photodissociation dynamics of n-C7H15Br molecule was investigated at different wavelengths of 231 to 239 nm by an ion imaging spectrometer operated under optimal conditions for velocity mapping, where the ions were generated from （2＋1） resonance enhanced ionization （REMPI） of the photofragments Br（^2P3/2） and Br^＊ （2P1/2） at the same wavelength as that of the photolysis laser. The released kinetic energies and the angular distributions of both fragments at different photolysis wavelengths were derived from the three-dimensional velocity images. The probabilities of the individual pathways of the fragments at 234 nm were calculated from the relative quantum yield and angular distribution. The total translational energy distributions were interpreted using soft impulsive model. The anisotropy parameter for Br^＊ is sensitive to the photolysis wavelength. This fact can be explained by the adiabatic and nonadiabatic dissociation processes in the electronically excited states of n-C7H15Br.

关 键 词：n-C7H15Br 离子速度成像 光解反应动力学 

分 类 号：O643.12[理学—物理化学]