Colley Jason E, Dynak Nathan J, Blais John R C, Duncan Michael A
Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States.
J Phys Chem A. 2024 Dec 12;128(49):10507-10515. doi: 10.1021/acs.jpca.4c05703. Epub 2024 Nov 25.
Tunable laser photodissociation spectroscopy and photofragment imaging experiments are employed to investigate the spectroscopy and dissociation dynamics of the Mg(benzene) ion-molecule complex. When excited with ultraviolet radiation, Mg(benzene) photodissociates efficiently, producing both Mg and benzene fragments, with branching ratios depending on the wavelength. The wavelength dependence of these processes are similar, with intense resonances at 330 and 241 nm and weaker features at 290 and 258 nm. Comparisons of the experimental spectra to those predicted by computational chemistry at the TD-DFT level allow assignment of these to metal ion-based (330 and 241 nm), charge-transfer (290 nm), and benzene-based (258 nm) transitions. However, the observation of the benzene cation fragment at all wavelengths, which can only result from charge-transfer, indicates unanticipated excited state dynamics. Spectroscopy experiments are complemented by photofragment imaging to investigate these dynamics. The high kinetic energy release indicates that multiphoton absorption based on the intense atomic resonances is responsible at least in part for the dissociation processes.
采用可调谐激光光解离光谱和光碎片成像实验来研究Mg(苯)离子-分子复合物的光谱和离解动力学。当用紫外辐射激发时，Mg(苯)会有效地光解离，产生Mg和苯碎片，其分支比取决于波长。这些过程的波长依赖性相似，在330和241 nm处有强烈的共振，在290和258 nm处有较弱的特征。将实验光谱与TD-DFT水平的计算化学预测光谱进行比较，可以将这些共振归属于基于金属离子的跃迁(330和241 nm)、电荷转移跃迁(290 nm)和基于苯的跃迁(258 nm)。然而，在所有波长下都观察到苯阳离子碎片，而这只能由电荷转移产生，这表明存在意想不到的激发态动力学。光谱实验通过光碎片成像进行补充，以研究这些动力学。高动能释放表明基于强烈原子共振的多光子吸收至少部分地导致了解离过程。
