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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

乙炔在最低三重态（T_1）有三个局部极小值，分别位于顺式、反式和亚乙烯基构型。这些构型之间的异构化反应受到了广泛的关注。我们用近红外半导体激光动力学光谱结合脉冲汞光敏化反应，在7400 cm ~ 2附近的顺式弯曲构型上观察到T_2 - T_1势能面之间的电子跃迁<-1>。对C_2H_2，C_2HD和C_2D_2的0-0带进行了转动分析，发现在C_2H_2的最低三重态的某些特定Ka态上存在严重的非均匀转动微扰，而在C_2HD和C_2D_2中没有观察到这种微扰。最低三重态振动基态Ka=1态的微扰子是一个谜。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，有一个PO ...更多信息在T_2和T_1表面上都有一个小势垒的反式异构体构型处的势能极小值。在T_2的情况下，反式最小值预计低于顺式。因此，顺式和反式之间的相互作用应该是预期的，特别是当一些振动模式被激发时。最近，我们分别在8170和7970 cm ~ 2区域观察到C_2H_2和C_2D_2的1-0带<-1>，其中顺式弯曲振动模被激发。通过组合差异的旋转分析，识别出更多的强扰动。此外，围绕C=C轴的转动常数由于振动激发而异常增大。这种强科里奥利型相互作用可能暗示了异构化反应的可能性，因为Ka的旋转量子数（其是沿C=C轴的角动量沿着）在包括线性构型的异构化中可以是恒定的运动。为了讨论顺式（C_<2v>）和反式（C_<2h>）组态等不同点群之间的相互作用，应引入完全核置换反转群G_8作为一个公共的对称平台。少