Photodiode Array Detection in Analytical High-Resolution Molecular Luminescence Spectroscopy

Abstract

It is shown that photodiode arrays can be successfully applied for the detection of highly resolved molecular luminescence spectra for analytical purposes. Instrumental resolution of 0.2 nm, sufficient for the discrimination of structural isomers like monomethylated polynuclear aromatic hydrocarbons, is readily achieved when a suitable monochromator is used. In the experimental setup employed in this study, only a limited spectral region (i.e., about 10 nm) can be observed at a time, but this is no problem when structurally related compounds are studied. These results imply that the detection of highly resolved emission spectra “on-the-fly,” as is required for on-line detection of chromatographically separated compounds in supersonic jets, will be possible. Furthermore, photodiode array detection enables the elimination of time-dependent effects [such as hole burning effects in Fluorescence Line-Narrowing (FLN)] in the spectra. In order that sensitivities similar to those of photomultipliers can be achieved, intensified photodiode arrays are needed.