Pulsed Optoacoustic Spectroscopy for Calorimetry without a Standard

A method which relies on no reference absorber to deduce yields for heat deposition following pulsed laser irradiation is described. Pulsed optoacoustic detection is used and signals are calibrated based on the excitation wavelength dependence of the heat yield. The apparatus is used to measure flourescence yields of several well known dyes in methalon solution. It is also demonstrated on a monolayer of dye absorbed to sapphire where no reference would be available. This technique was originally developed to measure pulsed temperature rises in stained mitochondria. The idea there is to assist in choosing an appropriate staining dye for selective thermal denaturation of proteins in cancerous cells by pulsed laser heating.