The fluorescence excitation spectra of single organic molecules in a solid state crystal are measured at cryogenic temperatures using a single frequency tunable laser light source based on optical parametric oscillator technology. This laser exhibits promising features as a light source for spectroscopy applications, including a broad tuning range from 450 to 650 nm, narrow linewidth < 1 MHz and mode-hop-free tuning over > 25 GHz. This application note presents the experimental setup, measured spectra and discusses the applicability of this kind of laser for high-resolution spectroscopy.

Fluorescence spectroscopy has been used to characterise natural organic matter (NOM) in water. Excitation-emission maps reveal the nature and concentration of NOM in river water and can be used as a routine analysis technique in water treatment facilities.