Study on optically forbidden excited states by photodetachment threshold electron spectroscopy

由于对称性选择规则和自旋守恒等限制，从基态到激发态是光学禁止的。本研究旨在利用光剥离阈电子能谱技术寻找这些激发态，并结合其他光谱技术阐明它们的本质。（1）分子氯的离子对状态：通过B^3 Ⅱ（0^+_）态的光-光双共振，确定了由于Franck-Condon限制而不能从基态到达的0^+_（^3P_0）态，并通过A^3 Ⅱ（1_u）-B '^3 Ⅱ（0^-_）相互作用态，利用微扰促进的光双共振，确定了0^-_（^3P_1）态.确定了这些激发态的势能函数。（2）NO_3自由基的电子激发态：利用组合差从红外吸收带确定了^2A_2基态的分子常数 ...更多信息 在红外区发现了禁戒激发态（^2E”）。利用塞曼调制，该谱被归属为到^2A”_1电子振动态的平行跃迁，其中e”振动通过激发态的电子振动相互作用打破了Born-Oppenheimer近似。（3）HOCl的电子激发态：当我们光解在平流层臭氧平衡中起重要作用的HOCl自由基时，OH碎片的速度沿着266 nm处光解光的电子矢量。该波长的光吸收是通过2^1A '-1^1A'跃迁进行的，跃迁矩平行于O-Cl轴。另一方面，在355 nm的光解中，OH碎片垂直于光解光的电子矢量排列，表明发生了1^1A”-1^1A'跃迁。因此，HOCl仅通过单重激发态光解离，这与HOBr的情况下可以通过三重态发生光解离的事实相反。少

There are the excited states which are optically forbidden to access from the ground state due to several restrictions, such as the symmetrical selection rules and the spin conservation. This study aimed to find these excited states by photodetachment threshold electron spectroscopy, and to elucidate their nature in combining with other spectroscopic techniques.(1)Ion-pair states of molecular chlorine : The 0^+_(^3P_0) states inaccessible from the ground states due to the Franck-Condon restriction was identified by optical-optical double resonance through the B^3II(0^+_) state.The 0^-_(^3P_1) state was also accessed through the A^3II(1_u)-B'^3II(0^-_) interacting states by perturbation-facilitated optical double resonance. The potential functions of these excited states were determined.(2)Electronically excited states of NO _3 radical : The molecular constants of the ^2A_2 ground stats are determined from the infrared absorption band using the combination differences.The symmetrically … More forbidden excited state (^2E") was found in the infrared region. using the Zeeman modulation, the specturm was assigned as the parallel transition to the ^2A"_1 vibronic state in which the e" vibration broke the Born-oppenheimer approximation through the vibronic interaction in the excited state.(3)Electronically excited states of HOCl : When we photodissociate the HOCI radical which is important in the stratospheric ozone balance, the OH fragment showed its velocity to be aligned along the electronic vector of the photolysis light at 266 nm. The photoabsorption at this wavelength proceeds through 2^1A'-1^1A' transition whose transition moment is parallel to the O-Cl axis. On the other hand, in the photolysis at 355nm, the OH fragments were aligned perpendicular to the electronic vector of photolysis light, indicating that the 1^1A"-1^1A'transition occurred. Consequently, HOCl is photodissociated only through the singlet excited states, which is in contrast with the fact that the photodissociation can occur through a triplet state in the case of HOBr. Less