Photoacoustic elastic bending in thin film—Substrate system

Todorović, D. M.; Rabasović, Mihailo D.; Markushev, D. D.

doi:10.1063/1.4839835

Cited by 25 publications

(33 citation statements)

References 32 publications

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“…The photoacoustic response of the two-layer sample irradiated with the modulated light source (Figure 1) [16,17,20] can be theoretically described by the total PA signal ( ) total pf  defined with the simple equation [13,14]:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Such film should be made of a material that does not generate charge carriers at the light source wavelength, transparent to allow direct membrane excitation, having the thickness relatively large enough to be visible in photoacoustic measurements. Titanium dioxide (TiO2), with which we already have experience in working with plasma-thick samples [16,17], appears to be a good thin film candidate.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Markushev

Aleksić

et al. 2022

Journal of Applied Physics

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The reduction of the photogenerated charge carriers' influence in periodically illuminated thin silicon membranes is investigated by using the experimental setup of an open photoacoustic cell in the standard range of modulation frequencies from 20 Hz to 20 kHz. It is confirmed that the deposition of a 200 nm thin film of titanium dioxide on the 30- and 50 μm silicon membrane leads to a large increase of the thermoelastic component of the photoacoustic signal, which restores the flexibility lost to the membrane under the influence of photogenerated carriers. The effect of the thermoelastic component enhancement is analyzed by observing the displacement of the tested samples along the heat propagation axis, depending on the carrier density and temperature differences on the illuminated and unilluminated sides, for different membrane thicknesses and a constant film thickness. It is found that the effect of enhancement of several orders of magnitude is more visible in thinner membranes due to higher ratios between the film and membrane thicknesses.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Markushev

Aleksić

et al. 2022

Journal of Applied Physics

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“…First, there is a big influence of noise that comes from different sources. Second, there is some influence of the instruments applied within the experimental system that distorts the signal, especially at the ends of the frequency interval (Markushev et al, 2015;Todorović et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Electro-acustic influence of the measuring system on the photoacoustic signal amplitude and phase in frequency domain

Aleksić

Markushev

Rabasović

et al. 2016

Facta Univ Phys Chem Technol

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The paper discusses the most common impacts of the measuring system on the amplitude and phase of the photoacoustic signals in the frequency domain using the opencell experimental setup. The highest signal distortions are detected at the ends of the observed modulation frequency range from 20 Hz to 20 kHz. The attenuation of the signal is observed at lower frequencies, caused by the electronic filtering of the microphone and sound card, with characteristic frequencies of 15 Hz and 25 Hz. At higher frequencies, the dominant signal distortions are caused by the microphone acoustic filtering, having characteristic frequencies around 9 kHz and 15 kHz. It has been found that the microphone incoherent noise, the so called flicker noise, is negligibly small in comparison to the signal and does not affect the signal shape. However, a coherent noise originating from the power modulation system of the light source significantly affects the shape of the signal in the range greater than 10 kHz. The effects of the coherent noise and measuring system influence are eliminated completely using the relevant signal correction procedure targeting the photoacoustic signal generated by the sample.

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“…Resonant peaks observed in this part of frequency domain are, throughout literature, attributed to the influence of measurement chain, although, in measurements, they occur at frequencies lower than expected (frequency characteristic of the microphone, the amplifier, and other electronics) [27][28][29]. Minimum volume cell has already been observed as an electro-acoustic resonator and it has been modeled with cascade filter array, with transfer function represented as the combination of two Helmholtz resonators:…”

Section: Helmholtz Resonances-the Influence Of the Measurement Chainmentioning

confidence: 99%

Developing the Techniques for Solving the Inverse Problem in Photoacoustics

Nesic

Popović

Galović

2019

Atoms

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In this work, theoretically/mathematically simulated models are derived for the photoacoustic (PA) frequency response of both volume and surface optically-absorbing samples in a minimum volume PA cell. In the derivation process, the thermal memory influence of both the sample and the air of the gas column are accounted for, as well as the influence of the measurement chain. Within the analysis of the TMS model, the influence of optical, thermal, and elastic properties of the sample was investigated. This analysis revealed that some of the processes, characterized by certain sample properties, exert their dominance only in limited modulation frequency ranges, which are shown to be dependent upon the choice of the sample material and its thickness. Based on the described analysis, two methods are developed for TMS model parameter determination, i.e., sample properties which dominantly influence the PA response in the measurement range: a self-consistent procedure for solving the exponential problems of mathematical physics, and a well-trained three-layer perceptron with back propagation, based upon theory of neural networks. The results of the application of both inverse problem solving methods are compared and discussed. The first method is shown to have the advantage in the number of properties which are determined, while the second one is advantageous in gaining high accuracy in the determination of thermal diffusivity, explicitly. Finally, the execution of inverse PA problem is implemented on experimental measurements performed on macromolecule samples, the results are discussed, and the most important conclusions are derived and presented.

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Photoacoustic elastic bending in thin film—Substrate system

Cited by 25 publications

References 32 publications

Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Electro-acustic influence of the measuring system on the photoacoustic signal amplitude and phase in frequency domain

Developing the Techniques for Solving the Inverse Problem in Photoacoustics

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