Finite Element Analysis Modeling of Pulse-Laser Excited Photothermal Deflection (Mirage Effect) from Aerosols

Abstract

A finite element analysis method for numerical modeling of the photothermal deflection spectroscopy of aerosols is presented. The models simulate pulse-laser excited photothermal deflection from aerosols collected on a plane surface substrate in air medium. The influence of the aerosol and substrate properties on the transient photothermal deflection signal is examined. We have previously obtained experimental results for photothermal deflection spectrometry of aerosols deposited onto a plate from an impactor system (O. O. Dada and S. E. Bialkowski, Appl. Spectrosc. 62, 1336 (2008)). This paper supports the validity of the experimental results presented in that paper and helps in answering some of the questions raised. The modeling results presented here demonstrate that the (peak) normalized transient temperature change profile and (peak) normalized transient photothermal deflection profile are a good approximation and invariant with number of particles, inter-particle distance, and particulate shape, which suggests that the photothermal deflection signal amplitude may be calibrated linearly with total mass of aerosols and the method could be applied to analysis of complex aerosols.

Development of Infrared Photothermal Deflection Spectroscopy (Mirage Effect) for Analysis of Condensed-Phase Aerosols Collected in a Micro-Orifice Uniform Deposit Impactor

“…The paper shows invariance of transient photothermal deflection signal on shape, number of particles, and inter-particle spacing. 27 The results also indicate that the signal magnitude is relatively stable with substrate thermal properties especially with high absorbance particles. This paper shows that experimental results are in good agreement with the numerical results.…”

Advanced Cellulosic Materials for Treatment and Detection of Industrial Contaminants in Wastewater

“…PDS is very promising for sorption detection, and provides very sensitive determination of various analytes . Iron(II) chelate with ferrozine has been selectively detected by sorption preconcentration, with limit of detection being 8 × 10 −12 and limit of quantification being 2.5 × 10 −11 mol cm −2 …”

“…[91][92][93] Iron(II) chelate with ferrozine has been selectively detected by sorption preconcentration, with limit of detection being 8 3 10 À12 and limit of quantification being 2.5 3 10 À11 mol cm À2 . [94] It is shown that the due regard to the changes in the chemistry at the trace level increases both the sensitivity and the selectivity of PT determination of these species compared to conventional spectrophotometry. [68,70,95,96] As a whole, the advantages of thermal-lens spectrometry over spectrophotometry from the viewpoint of procedure development and complex characterization are summarized below in Figure 10.…”

Photoacoustic Technique Applied to Measurement of Particulate Matter Deposits

“…8 Esto impone una cota máxima sobre el radio que deben tener las partículas para obtener un intercambio de calor eficiente a una dada frecuencia de excitación. Acorde a esto y a (1) se puede inferir que la señal FA depende no solo de la masa iluminada, a través de  sino del tamaño de las partículas depositadas, a partir de f 7,17 .…”