Numerical Simulation of Photothermal Lens Spectrometry Models Relevant for Analytical Chemistry

Three numerical models (radial symmetry two-dimensional and three-dimensional with cw and pulsed excitation) that correspond to the samples and schematics of dual-beam thermal lens measurements in solution most commonly used in chemical analysis are implemented by finite element analysis using COMSOL Multiphysics and geometry simulations using MATLAB. The comparison of the results obtained using the implemented models with the existing infinite two-dimensional model by Shen and Snook (J Appl Phys 73(10):5286, 1993.  https://doi.org/10.1063/1.353761) under the same conditions showed their good agreement. The models were used to study the influence of the basic geometric and physical parameters of the sample. Conditions are found under which the boundary conditions for heat transfer and the geometrical parameters of the cell have the strongest and weakest effects on the signal.