Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland.
J Chem Phys. 2010 Aug 28;133(8):081103. doi: 10.1063/1.3472312.
We employ triple-resonance vibrational overtone excitation to access quasibound states of water from several fully characterized bound states of the molecule. Comparison of the measured dissociation spectra allows a rigorous assignment of rotational quantum numbers J, nuclear spin and parity, and a tentative vibrational characterization of the observed resonances. Their asymmetrical shapes (Fano profiles) reflect interference of dipole moments for transitions to these resonances with that to the dissociative continuum. The assignments and Fano profile parameters of the resonances stand as a benchmark for the extension of accurate quantum-mechanical calculations to activated complexes of water. The narrow widths of some of these resonances indicate that water molecules may survive for as long as up to 60 ps in states above the dissociation threshold. We consider the possible implication of such long-lived states for the kinetics of water dissociation and the OH+H association reaction.
我们采用三重共振振动泛频激发技术，从分子的几个完全特征化的束缚态获取水的准束缚态。对测量的离解光谱的比较允许对观察到的共振的转动量子数 J、核自旋和宇称进行严格的分配，并对其振动特性进行初步确定。它们的不对称形状（Fano 轮廓）反映了跃迁到这些共振的偶极矩与离解连续体的偶极矩的干涉。共振的分配和 Fano 轮廓参数是将精确量子力学计算扩展到水的活化复合物的基准。其中一些共振的狭窄宽度表明，水分子可能在离解阈值以上的状态中存活长达 60 ps。我们考虑了这种长寿命状态对水离解动力学和 OH+H 缔合反应的可能影响。
