Mathematical expressions for the shape and amplitude of photoacoustic signal generated due to the multi-photon absorption of Gaussian laser pulses are derived. It was found out that the sensitivity of photoacoustic spectrometer increases in proportion to n3/4, where n is the nonlinearity degree, when the absorption is changed from linear one-photon to nonlinear multi-photon one. The calibration of photoacoustic spectrometer, used in the measurements of multi-photon absorption cross sections, are discussed.
multi-photon absorption, calibration of photoacoustic spectrometer