SOLVENTS EFFECTS IN DETERMINATION OF ANTHRACENE ON SOLUTION SURFACES BY LASER 2-PHOTON IONIZATION TECHNIQUE

The photoionization charge (area of the signal) of anthracene on the solution surface has been measured for various solvents using the third harmonic of an NdYAG laser (355 nm). The charge was quadratically proportional to the laser pulse energy, indicating a two-photon process. It saturated quickly at a higher bias voltage. It increased drastically with increasing dielectric constant of the solvent when the solvent was polar. It increased with increasing electron mobility of the solvent when the solvent was nonpolar. Water, which has the largest dielectric constant among the solvents used, gave the largest signal and the lowest detection limit.