Annesley Christopher J, Berke Andrew E, Crim F Fleming
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
J Phys Chem A. 2008 Oct 2;112(39):9448-53. doi: 10.1021/jp803901p. Epub 2008 Aug 5.
State-resolved reactions of CH3D molecules containing both C-H and C-D stretching excitation with Cl atoms provide new vibrational spectroscopy and probe the consumption and disposal of vibrational energy in the reactions. The vibrational action spectra have three different components, the combination of the C-H symmetric stretch and the C-D stretch (nu1 + nu2), the combination of the C-D stretch and the C-H antisymmetric stretch (nu2 + nu4), and the combination of the C-D stretch and the first overtone of the CH3 bend (nu2 + 2nu5). The simulation for the previously unanalyzed (nu2 + nu4) state yields a band center of nu0 = 5215.3 cm(-1), rotational constants of A = 5.223 cm(-1) and B = 3.803 cm(-1), and a Coriolis coupling constant of zeta = 0.084. The reaction dynamics largely follow a spectator picture in which the surviving bond retains its initial vibrational excitation. In at least 80% of the reactive encounters of vibrationally excited CH3D with Cl, cleavage of the C-H bond produces CH2D radicals with an excited C-D stretch, and cleavage of the C-D bond produces CH3 radicals with an excited C-H stretch. Deviations from the spectator picture seem to reflect mixing in the initially prepared eigenstates and, possibly, collisional coupling during the reaction.
含有C - H和C - D伸缩振动激发的CH3D分子与Cl原子的态分辨反应提供了新的振动光谱，并探测了反应中振动能量的消耗和处置。振动作用光谱有三个不同的组分，C - H对称伸缩振动和C - D伸缩振动的组合（ν1 + ν2）、C - D伸缩振动和C - H反对称伸缩振动的组合（ν2 + ν4）以及C - D伸缩振动和CH3弯曲的第一泛频的组合（ν2 + 2ν5）。对先前未分析的（ν2 + ν4）态的模拟得到带中心ν0 = 5215.3 cm⁻¹、转动常数A = 5.223 cm⁻¹和B = 3.803 cm⁻¹以及科里奥利耦合常数ζ = 0.084。反应动力学很大程度上遵循旁观者图像，其中幸存的键保留其初始振动激发。在振动激发的CH3D与Cl的至少80%的反应碰撞中，C - H键的断裂产生具有激发的C - D伸缩振动的CH2D自由基，C - D键的断裂产生具有激发的C - H伸缩振动的CH3自由基。与旁观者图像的偏差似乎反映了初始制备的本征态中的混合，以及可能的反应过程中的碰撞耦合。
