Experimental and numerical investigation of photoacoustic resonator for solid samples

TL;DR

This paper combines experimental measurements and numerical modeling to analyze a photoacoustic resonator for solid samples, demonstrating good agreement and proposing a faster simulation method.

Contribution

It introduces an amplitude mode expansion model for photoacoustic resonators that is faster and less computationally demanding than existing viscothermal models.

Findings

Measured resonances closely match numerical predictions with less than 1.8% deviation.

The amplitude mode expansion model effectively reproduces resonance frequencies.

Differences between models are explained by antinode location effects.

Abstract

The photoacoustic signal in a closed T-cell resonator is generated and measured using laser based photoacoustic spectroscopy. The signal is modelled using the amplitude mode expansion method, which is based on eigenmode expansion and introduction of losses in form of loss factors. The measurement reproduced almost all the calculated resonances from the numerical models with fairly good agreement. The cause of the differences between the measured and the simulated resonances are explained. In addition, the amplitude mode expansion simulation model is established as a quicker and computationally less demanding photoacoustic simulation alternative to the viscothermal model. The resonance frequencies obtained from the two models deviate by less than 1.8%. It was noted that the relative height of the amplitudes of the two models depended on the location of the antinodes within the resonator.