Experimental Studies for structure and Isomerization Dynamics of Triplet Acetylene

三线态乙炔的结构和异构化动力学实验研究

• 批准号: 08454178
• 负责人: KANAMORI Hideto
• 金额: $ 4.93万
• 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: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454178/
• 关键词: triplet metastable stable; isomerism reaction; intersystem crossing; isotopt effect; high resolution spectroscopy; kinetic spectroscopy; triplet acetylene; 異性化反応ダイナミクス; 高分解能光分光; 項間交叉; アセチレン電子緩和; 三重項励起状態; 内部転換

The triplet states of normal and deuteride acetylene were generated by mercury photo-sensitized techniques and were detected by using near infrared diode laser spectroscopy. A thousand of absorption lines were observed in Doppler limited resolution in the 7300-7500 cm^-^1 and were assigned to the electronic transition from a ^3B_2 to d ^3A_2 state. The intensity alternation due to two equivalent protons or deuterons appeared in the asymmetry (K-)doubling clearly showed that the structure of the triplet acetylene is cis-bent. The band origin and rotational constants agrees well to a previous low resolution study and recent theoretical results. Spin rotation and spin-spin interaction constants determined are consistent among C_2H_2. C_21-D and C_2D_2.A kinetic future of the triplet state was also studied in order to reveal the interaction between the triplet and singlet states. The transient absorption profiles along the time axis were measured by using diode laser kinetic spectroscopy combined with a pulsed mercury photo-sensitized method. The lifetime at the collision free condition was extrapolated by Stern-Volmer analysis. The natural lifetime of a ^3B_2 state of C_2H_2 is about 4xl0^-^5 second. which is independent to the rotational states and spin states(F_1.F_2, F_3). However, the lifetime of C_2D_2 is three times longer than that of C_2H_2. These results would be a key point for understanding the internal conversion mechanism from the bent triplet excited state to the linear singlet ground state.

用汞光敏技术产生了正乙炔和氘乙炔的三重态，并用近红外半导体激光光谱进行了探测。在7300-7500 cm^-1范围内，在多普勒极限分辨率下观测到了1000条吸收谱线，这些谱线被归属于从a^3B_2到d^3A_2态的电子跃迁。在不对称（K-）倍频中出现的两个等效质子或氘的强度交替清楚地表明三重态乙炔的结构是顺式弯曲的。带的起源和转动常数同意以及以前的低分辨率研究和最近的理论结果。C_2H_2的自旋转动和自旋-自旋相互作用常数的测定结果是一致的。C_21-D和C_2D_2。为了揭示三重态和单重态之间的相互作用，还研究了三重态的动力学性质。利用半导体激光动力学光谱结合脉冲汞光敏化方法测量了样品沿着时间轴的瞬态吸收曲线。通过Stern-Volmer分析外推在无碰撞条件下的寿命。C_2H_2的^3B_2态的自然寿命约为4 × 10 ^-^5秒。它与转动态和自旋态（F_1.F_2，F_3）无关。而C_2D_2的寿命比C_2H_2的寿命长3倍。这些结果将是理解从弯曲三重激发态到线性单重基态的内转换机制的关键。

项目成果

M.McCarthy, H.Kanamori, R.W.Field: "Sideband Optical-Optical Double Resonance Zeeman Spectroscopy II." J. Chem. Phys.107. 4179-4188 (1997)

M.McCarthy、H.Kanamori、R.W.Field：“边带光学-光学双共振塞曼光谱 II”。