The eigenstate-resolved, high-resolution (5 MHz) infrared spectrum of the asymmetric &dbond;CH2 hydride stretch of isobutene has been measured using an electric resonance optothermal spectrometer (EROS). This vibrational band near 3087 cm-1 was rotationally assigned with ground state microwave-infrared double-resonance spectroscopy. IVR rates from rotationally homogeneous IVR multiplets at values of total angular momentum, J ranging from J = 0 to J = 3 and Ka values of Ka = 0 to Ka = 2, were obtained. The average IVR lifetime for this vibrational mode is 105 ps and independent of rotational state. The experimental state density of the rotationless 000 vibrational state, approximately 150 states/cm-1, is in good agreement with the direct count result of 99 states/cm-1 using the C+3 v multiply sign in circle C-3 v (G36) molecular symmetry group. The lineshape profiles of the IVR multiplets are investigated in order to elucidate information concerning the dependence of IVR rates on the symmetry of the torsional wavefunction. We find that there is a common IVR rate among the various torsional symmetries. IVR lifetimes observed in the present study are compared to other asymmetric ethylenic hydride stretch IVR rates measured in our laboratory. Copyright 1999 Academic Press.

中文翻译：

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异丁烯不对称 CH2Hydride 拉伸的分子内振动动力学

使用电共振光热光谱仪 (EROS) 测量了异丁烯的不对称 &dbond;CH2 氢化物拉伸的本征态分辨的高分辨率 (5 MHz) 红外光谱。这个 3087 cm-1 附近的振动带被旋转分配了基态微波-红外双共振光谱。获得了在总角动量值 J 范围从 J = 0 到 J = 3 和 Ka = 0 到 Ka = 2 的 Ka 值时旋转均匀 IVR 多重峰的 IVR 率。这种振动模式的平均 IVR 寿命为 105 ps，与旋转状态无关。无旋转 000 振动态的实验态密度，大约为 150 个态/cm-1，与使用圆 C-3 v 中的 C+3 v 乘法符号的 99 个态/cm-1 的直接计数结果非常吻合（ G36) 分子对称群。研究了 IVR 多重峰的线形轮廓，以阐明有关 IVR 速率对扭转波函数对称性的依赖性的信息。我们发现在各种扭转对称性之间存在共同的 IVR 率。本研究中观察到的 IVR 寿命与我们实验室测量的其他不对称氢化乙烯拉伸 IVR 率进行了比较。版权所有 1999 学术出版社。