Convective Effects in Thermal Lens Spectroscopy

Abstract

Thermally induced solution stirring can cause periodic signal fluctuations which can be the sensitivity limiting factor in thermal lens spectroscopy with a chopped pump laser. Pump and probe laser fluctuations are shown to be random, while thermal lens signals are shown to have a small periodic component caused by stirring. The problem is serious in dilute solutions because of the high solvent background absorbance.