Double-resonant second harmonic generation from surface coverages of Nile Blue A

Abstract

Second harmonic emission from a dye covered quartz surface was obsd. in total internal reflection. Coverages with the dye Nile Blue A yielded an increase in 2nd harmonic output by several orders of magnitude as compared to coverages with Rhodamine 6G. In the latter case, only the harmonic light is at resonance with the S0-S2 transition of the adsorbed dye mols., whereas for Nile Blue A both, the fundamental and the harmonic frequency, are at resonances with the resp. singlet transitions.