Structure and reaction dynamics in gas phase solute-solvent heteroclusters

我们进行了以下两个项目，并取得了一些有趣的结果。（1）研究了9，9 ′-联蒽基（BA）与乙腈（ACN）、BA-（ACN）_n（n=1-5）的气相团簇的电子激发态动力学。测量了质量选择双色共振增强多光子电离（REMPI）光谱，以确定具有特定数目乙腈分子的BA簇合物的吸收带。测量了这些吸收带的色散荧光光谱和寿命，研究了BA-（ACN）_n团簇中BA的激发态动力学。对于所研究的所有簇合物，DF光谱较宽，并且与未簇合的BA相比发生了很大程度的红移。BA在团簇中的荧光寿命明显长于未成团的BA。这些结果表明，在团簇中BA的光激发态转变为极性激发态，类似于分子内的扭曲电荷转移 关于我们 转移（TICT）状态的BA在乙腈溶液中。BA-（ACN）_1的斯托克斯位移和寿命表明，加入一种乙腈即可进行电荷转移反应。然而，这两个性质的较大的集群并没有表现出单调变化的BA在乙腈溶液中。这些结果表明，团簇的结构和动力学在电荷转移反应中起着重要的作用。（2）将激光诱导荧光技术应用于电喷雾细胞色素c（cyt-c）的研究。虽然对于中性pH溶液的电喷雾没有观察到荧光，但是对于通过乙酸酸化的溶液的喷雾观察到归因于异硫氰酸酯残留物的荧光。观察到来自酸化cyt-c的荧光的相对强度随着距喷雾针末端的距离而增加。该结果表明，由于电喷雾中溶剂分子的损失，异硫氰酸酯残基变得更加荧光。有人建议，高度带电的cyt-c离子，保持溶液中的非荧光紧凑的形式，使构象的变化，在电喷雾溶剂的损失，并成为荧光。少

We have carried out the following two projects and obtained some interesting results.(1)Dynamics of the electronically excited state of 9,9'-bianthryl(BA) was studied in gas-phase clusters with acetonitrile (ACN), BA-(ACN)_n(n=1-5). The mass-selected two-color resonance-enhanced multiphoton ionization (REMPI) spectra were measured to determine the absorption band for the cluster of BA with the specific number of the acetonitrile molecules. The dispersed fluorescence (DF) spectra and lifetimes were measured for these absorption bands to study the dynamics of the excited state of BA in the clusters, BA-(ACN)_n. For all clusters studied, the DF spectra were broad and largely red shifted compared with that of unclustered BA. The fluorescence lifetimes of BA in the clusters were considerably longer than that of unclustered BA. These results suggested that the photoexcited state of BA in the clusters change to the polar excited state which is analogous to the twisted intramolecular charge tr … More ansfer (TICT) state of BA in the acetonitrile solution. Stokes shift and lifetime of the BA-(ACN)_1 suggested that the charge-transfer reaction becomes possible by adding one acetonitrile. However, these two properties of the larger clusters did not show monotonic change toward those of BA in acetonitrile solution. These results implied that the structure and dynamics of the clusters play some important roles in the charge-transfer reaction.(2)The laser-induced fluorescence technique is applied to electrosprayed cytochrome c (cyt-c). While no fluorescence was observed for the electrospray of the solution of neutral pH, the fluorescence ascribed to the tryptophane residue was observed for the spray of the acidified solution by acetic acid. The relative intensity of the fluorescence from the acidified cyt-c is observed to increase with the distance from the end of the spray needle. This result indicates that the tryptophane residue becomes more fluorescent by the loss of solvent molecules in the electrospray. It is suggested that the highly charged cyt-c ions which preserve the nonfluorescent compact forms in solution make a conformational change by the loss of solvent in the electrospray and become fluorescent. Less