Abstract

Selectivity is a factor that limits practical chemical measurements in many analytically important situations either because the large number of components causes overlapping of distinguishing features or the features of any one component are broadened because of inhomogeneties within the sample. Site selective spectroscopy has been developed as a method for improving selectivity by reducing both types of problems. Fluorescence line narrowing was first developed by Szabo for eliminating inhomogeneous broadening in ruby crystals [1], it was extended to the elimination of inhomogeneous broadening in the spectra of polyaromatic hydrocarbons by Marchetti and coworkers [2], and it was adapted to analytical problems by Small and coworkers [3]. In this technique, a laser is tuned to a position within an inhomogeneously broadened band so that molecules in sites that are resonant with the laser are excited. The resulting fluorescence spectrum can be markedly sharpened because only a subset of the chromophores contribute and the inhomogeneous broadening can be eliminated.

© 1987 Optical Society of America