Theoretical aspects of photoacoustic spectroscopy with light scattering samples

Helander, P.

doi:10.1063/1.332455

Cited by 52 publications

(19 citation statements)

References 14 publications

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“…Moreover, scattered light, which presents such a serious problem in conventional spectroscopic techniques, presents less difficulty in PAS and can be solved by making necessary corrections. 33,34 The Li x Mn 2 O 4 pelletized polycrystalline samples under the present investigation are highly absorbing, and hence, optically opaque in the range of experiment. This means that the PA signal produced is solely due to surface light absorption, and light scattering has negligible effect on the signal.…”

Section: Introductionmentioning

confidence: 83%

Effect of lithium concentration on the thermal and optical properties ofLixMn2O4by photoacoustic measurements

et al. 2007

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In the present work, pellets of Li x Mn 2 O 4 polycrystalline powder samples with x = 0.8, 0.9, 1.0, 1.1, and 1.2 are analyzed to understand the effect of lithium concentration on the thermal and optical properties, and the electronic structure of Li x Mn 2 O 4 predicted in an earlier work using full-potential linear muffin-tin orbital ͑FP-LMTO͒ method is experimentally verified. The experimental tool used for the determination of the thermal and optical properties is the well-known photoacoustic technique. The variation of thermal diffusivity with changing x values in Li x Mn 2 O 4 is extensively studied to explain the influence of lithium concentration on the thermal properties, and has been correlated with the structural asymmetry and defects in Li x Mn 2 O 4 . The optical absorption spectrum, being the signature of the electronic structure of materials, is recorded in the visible range ͑350-800 nm͒. Six prominent absorption peaks associated with the O 2p-Mn t 2g , O 2p-Mn e g , and Mn t 2g -Mn e g band transitions for Li x Mn 2 O 4 , with x ഛ 1, are observed experimentally, substantiating the electronic structure predicted by the FP-LMTO method. However, it is observed that there are more absorption peaks in the case of Li 1.1 Mn 2 O 4 and Li 1.2 Mn 2 O 4 , which is attributed to the structural distortion from pure cubic spinel structure to a mixture of spinel and tetragonal structures, which is verified by the x-ray diffraction spectra.

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Section: Introductionmentioning

confidence: 83%

Effect of lithium concentration on the thermal and optical properties ofLixMn2O4by photoacoustic measurements

et al. 2007

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“…Another class of optical characterization problems accessed by photothermal methods in general 35 and n-PDS in specific, is the detection of light absorption and scattering profiles in diffusely scattering materials. A recent application was made to the characterization of artificially aged papers, 36 in which n-PDS was used to recover absolute values of the absorption, scattering and transmission coefficients, as well as thermal diffusivity measurements on the individual papers.…”

Section: Applicationsmentioning

confidence: 99%

Beam Deflection Photothermal Spectroscopy

Power

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Beam Deflection Principles Optical Principles Heat Diffusion Principles Collinear Photothermal Deflection Normal Photothermal Deflection Instrumentation and Measurement Applications

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“…Therefore, PAS is unique in the study of the absorption of light-scattering condensed sample [11] . The influence of light scattering effects on photoacoustic signal of condensed sample have been treated theoretically [12,13] and experimentally [14][15][16] . However, theoretical papers usually present the relationship between photoacoustic signal and the scattering coefficient, but fail to visualize the influence of light scattering effects on the photoacoustic spectrum of a sample.…”

Section: Introductionmentioning

confidence: 99%

Scattered light: improving photoacoustic spectral measurement with a drug tablet

Jiang

et al. 2013

SPIE Proceedings

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Photoacoustic spectroscopy (PAS) is a powerful tool for the study of the absorption spectra of solid samples.Scattered light, which used to be a main error source in conventional absorption spectroscopy, is not a problem for PAS, and furthermore, in this paper it is helpful for photoacoustic spectroscopy measurement. In this work, the photoacoustic spectra of an olanzapine tablet and its powder have been investigated. Differential analysis was used to eliminate the background signal generated by the photoacoustic cell. It is found that the photoacoustic spectrum of olanzapine in the powdered olanzapine tablet has the same spectral features as that of the pure olanzapine powder, while the photoacoustic spectrum of the olanzapine tablet does not have, although the ingredients in both are completely the same. This phenomenon can be interpreted as the light scattering effects in the powdered olanzapine tablet. The light scattering effects in a solid mixture amplify the photoacoustic spectral features of the main light-absorbing ingredient in the mixture, rather than enhance the measured photoacoustic signal over the whole measured wavelength range, which is different from the influence of light scattering effects on a single-ingredient solid powder. Based on this work, a method is proposed to preliminarily fast identify the light-absorbing ingredient in a solid mixture. Using the method, a drug tablet can be measured directly in solid state and hardly need sample preprocessing, and thus the time for composition analyses will be reduced significantly.

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Theoretical aspects of photoacoustic spectroscopy with light scattering samples

Abstract: A theoretical model for photoacoustic spectroscopy with light scattering samples is discussed. Some special cases are derived and the nature of the measured signal and the underlying physics are analyzed. Comparisons with transmission and diffuse reflectance spectroscopy are made.

Cited by 52 publications

References 14 publications

Effect of lithium concentration on the thermal and optical properties ofLixMn2O4by photoacoustic measurements

Effect of lithium concentration on the thermal and optical properties ofLixMn2O4by photoacoustic measurements

Beam Deflection Photothermal Spectroscopy

Scattered light: improving photoacoustic spectral measurement with a drug tablet

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