The electronic and molecular structure of radicals with a C=C core

具有 C=C 核心的自由基的电子和分子结构

基本信息

批准号：
11440172
负责人：
KANAMORI Hideto
金额：
$ 9.54万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Acetylene in the lowest triplet state (T_1) has three local minima at cis, trans, and vinylidene configurations according to theoretical calculations. Isomerization reaction among those configurations has been paid a lot of attentions. We have observed an electronic transition between the T_2 - T_1 potential surface at the cis-bent configuration around 7400 cm^<-1> region by using near-IR diode laser kinetic spectroscopy combined with a pulsed mercury photo-sensitized reaction. By now 0-0 band of C_2H_2, C_2HD and C_2D_2 have been rotationally analyzed and sever inhomogeneous rotational perturbations have been recognized in some specific Ka states in the lowest triplet state of C_2H_2, but no perturbations were observed in C_2HD and C_2D_2. The perturber for the Ka=1 state of vibrational ground state in the lowest triplet state is a mystery. One candidate for this perturbation is an interaction among the other isomers. Some high level ab initio calculations predicted that there is a po … More tential minimum at the trans-isomer configuration with a small potential barrier in both the T_2 and T_1 surfaces. In case of T_2, the trans minimum is predicted to be lower than the cis. Therefore, an interaction between the cis and trans should be expected, especially when some vibrational modes are excited. Recently we have observed 1-0 band of C_2H_2 and C_2D_2 in 8170 and 7970 cm^<-1> region, respectively, in which the cis-bent vibrational mode is excited. After the rotational analysis based on the combination difference, more sever perturbations have been recognized. Moreover, the rotational constant around the C=C axis is abnormally enlarged by the vibrational excitation. This strong Coriolis type interaction may suggest a possibility of the isomerization reaction because the rotational quantum number of Ka, which is the angular momentum along the C=C axis, can be a motion of constant in the isomerization including the linear configuration. In order to discuss such an interaction between different point groups as cis (C_<2v>) and trans (C_<2h>) configurations, Complete Nuclear Permutation Inversion group G_8 should be introduced as a common symmetrical platform. Less

根据理论计算，最低三重态（T_1）的乙炔在顺式、反式和亚乙烯基构型下具有三个局部最小值，这些构型之间的异构化反应受到了广泛关注。通过使用近红外二极管激光动力学光谱与脉冲汞相结合，在 7400 cm^<-1> 区域附近顺式弯曲构型的势表面到目前为止，C_2H_2、C_2HD 和 C_2D_2 的 0-0 能带已经被旋转分析，并且在 C_2H_2 的最低三重态中的一些特定 Ka 态中发现了严重的非均匀旋转扰动，但在 C_2HD 和 C_2HD 中没有观察到扰动。 C_2D_2。最低三重态的振动基态 Ka=1 态的扰动是 a这种扰动的一个候选者是其他异构体之间的相互作用。一些高水平的从头计算预测，在 T_2 和 T_1 表面均存在小势垒的反式异构体构型中存在潜在最小值。在 T_2 的情况下，预计反式最小值将低于顺式，因此，应该预期顺式和反式之间会发生相互作用，特别是当最近我们观察到 1-0 能带时。 C_2H_2和C_2D_2分别位于8170和7970 cm^-1>区域，其中激发了顺式弯曲振动模式。基于组合差异的旋转分析，发现了更严重的扰动。而且，旋转常数也被识别出来。 C=C 轴周围因振动激发而异常放大，这种强烈的科里奥利型相互作用可能表明由于旋转而发生异构化反应的可能性。 Ka 的量子数，即沿 C=C 轴的角动量，可以是包括线性构型在内的异构化中的常数运动，以便讨论不同点群之间的相互作用，例如 cis (C_<2v>)。和反式（C_<2h>）构型，应引入完全核置换反转群G_8作为通用对称平台。