Spectroscopic Studies of Unimolecular Reaction Dynamics of Vibronically State-selected Molecules

为了研究振动态选择的乙炔的振动动力学，应用了多种光谱技术：(1)从X^1Σ_g+态的v_3“态的选择转动能级J”可以获得乙炔A^1a_u态的未成熟的Nv_3‘+v_4’/v_6‘(n=0，1，2，3)振动态的振动能级系统。Nv_3‘+v_6’和Nv_3‘+v_4’态通过a轴和b轴的科里奥利力相互作用相互耦合。(2)3v_3‘+v_6’态的大部分转动能级分裂为两个或两个以上的能级，而3v_3‘+v_4’态的转动能级是单一的。在弱磁场作用下，从溢出能级开始的荧光衰减表现为量子拍频。这表明能级分裂是由S-T相互作用引起的。由于v_6‘模在平面内，而v_4’模在平面外，S-T相互作用发生在被激发的乙炔的平面几何结构中。(3)用氢原子作用谱研究了在47000~50600 cm^&lt；-1&gt；范围内激发态乙炔的预解离效率。超过弯曲振动反转势垒的态在48000 cm^&lt；-1&gt；附近时，预解离增强。

In order to investigate vibrational dynamics of vibronically state-selected acetylene, various spectroscopic techniques have been applied.(1) The rovibronic level system of the ungerade nv_3'+v_4'/v_6' (n=0,1,2,3) vibrational states in the A^1A_u state of acetylene which are accessible from the selected rotational level J" of the v_3" state in the X^1Σ_g^+ state. The nv_3'+v_6' and nv_3'+v_4' state are found to couple with each other by the a-and b-axis Coriolis interactions.(2) Most of rotational levels of the 3v_3'+v_6' state split into two or more levels, while those of the 3v_3'+v_4' state are single. The fluorescence decay from the spilit levels shows a quantum beat under a weak magnetic field. This indicates that the level splitting is attributable to the S-T interaction. Since the v_6' mode is in-plane while the v_4'is out-of-plane, the S-T interaction occurs in the planar geometry of the excited acetylene.(3) The H-atom action spectroscopy has been applied to investigate the predissociation efficiency of acetylene excited in the gerade vibrational states in the region of 47000〜50600 cm^<-1>. The predissociation is enhanced in the states exceeding the inversion barrier of the bending vibration which is located around 48000 cm^<-1>.