Photoacoustic cell for dynamic measurements with nanosecond time resolution

A design of a photoacoustic (PA) cell for dynamic measurements in liquid samples with nanosecond time resolution is presented. The design is based on a layered scheme of laser-induced sound excitation and detection. A theoretical basis for the use of the cell in dynamic PA diagnostics and in pulsed acoustic spectroscopy is given. The cell parameters which determine its performance in both applications are established, and ways of cell optimization are discussed. The validity of the theoretical description was proven in a set of calibration experiments. The functioning of the cell as a PA-diagnostics device was tested on a model photochemical system (the quenching of the triplet state of benzophenone by 2,5-dimethyl-2,4-hexadiene), With a slight modification the cell was used for pulsed broadband acoustic spectroscopy to probe the structural relaxation in formic acid in the frequency range of 2-20 MHz. (C) 1996 American Institute of Physics.