Structure and reaction dynamics in gas phase solute-solvent heteroclusters

(1)研究了9，9‘-联菲(BA)在含乙腈(ACN)、BA-(ACN)_n(n=1-5)的气相簇合物中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，确定了具有特定数目的乙腈分子的BA团簇的吸收带。测量了这些吸收带的色散荧光(DF)光谱和寿命，以研究BA-(ACN)n团簇中BA的激发态动力学.与未簇合的BA相比，所研究的所有团簇的DF光谱都较宽且红移很大.簇内BA的荧光寿命明显长于未簇化的BA。这些结果表明，团簇中BA的光激发态转变为类似于扭曲的分子内电荷tr…的极性激发态更多的转移(TICT)状态的BA在乙腈溶液。BA-(ACN)_1的斯托克斯位移和寿命表明，加入一个乙腈即可发生电荷转移反应。然而，在乙腈溶液中，较大团簇的这两个性质并没有表现出相对于BA的单调变化。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)。中性pH溶液的电喷雾没有观察到荧光，而醋酸酸化溶液的电喷雾则观察到属于色氨酸残基的荧光。观察到来自酸化的CyT-C的荧光的相对强度随着距离喷雾针末端的距离而增加。这一结果表明，由于溶剂分子在电喷雾中的损失，色氨酸残基变得更具荧光。结果表明，高电荷态的Cyt-c离子在溶液中保留了非荧光的致密结构，在电喷雾中由于失去了溶剂而发生构象变化，变成了荧光。较少

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