ELECTRIC AND MOLECULAR STRUCTURE INVESTIGATION

去年的进度报告是关于我们对溶剂的影响的研究

Last year's progress report on our studied of solvent effects on the spectra of indole through an investigation of indole clusters was found to be marred by an unrecognized technical problem. The results obtained, that the 284 nm indole band was shifted successively to the red by the successive addition of 1 - 13 n-hexane molecules is correct. However the observation that the hexane molecules is correct. However the observation that the spectral bands were broader than expected caused us to reexamine our work. We found that one molecule of the carrier gas used in most of our investigations, Ar, bound tightly to either indole or the cluster and perturbed the spectrum. When the experiments were repeated with He as the carrier gas the anticipated narrow spectral bands were obtained but it was not possible to attain large cluster sizes. We also investigated the discrepancy between the mechanism proposed for the hydrogen-binding spectral shift of the indole chromophore in solution, where the binding of both of H-donor and a H-acceptor was deduced to be necessary, and in the gas phase, where the only binding of the H-donor was deduced necessary. Our results indicate that binding the H-donor is necessary to produce the spectral shift but the H-acceptor binds first and remains firmly bound thereafter.