A microcomputer-controlled N2 gas laser photolysis system has been built for easy measurements of reliable transient absorption spectra. Shutters for optical path, wavelength-driving of monochromator and detection of analysing beam are controlled by a microcomputer, and obtained data are processed and given on a printer, a XY plotter, and a CRT. For examining this system, transient absorption spectra and their decay kinetics of cyclohexane solutions of 1, 2-benzanthracene and anthracene were measured and analysed, which are in agreement with published data on their triplet state. As typical examples, the following two studies are reported here. Fluorescene quenching of aromatic molecules by metal ions in aqueous solution was investigated, and the formation of the triplet state was confirmed. The application to polymer solutions leads to first observations of new polymer effects on ionic photo-dissociation processes.