The rotationally resolved electronic spectrum of indole in the gas phase

Abstract

The high resolution ultraviolet fluorescence excitation spectrum of indole in a supersonic jet has been measured. It was possible to resolve the rotational structure with an experimental resolution of 180 MHz. The details of the technique employed to achieve this resolution in the ultraviolet are described. Analysis of the high resolution spectrum yielded a transition moment direction which is compared to previous theoretical predictions. Application of high resolution spectroscopy to the problem of distinguishing the 1La and 1Lb electronic states in indole and indole derivatives is discussed. From the measured rotational constants possible geometries for the ground and excited states were also determined.