I have several organic powder component mixtures. The concentration of one of the components changed into the mixtures in the range 1...10%. Samples are monolayer of powder particles, fixed on low luminescence substrate. I measure spectra of photoluminescence, they are characterized as wideband ~200 nm width. Distinguish which part of this band related to which component is not possible, they are strongly overlapped.
When I measure spectra of photoluminescence as a function of variable component concentration, I found that both band total intensity, as well as its peak value, inversely depends on component's concentration: bigger concentration corresponds to lower total and peak intensities. Plot intensity as a function of 1/concentration is close to the linear one.
Which mechanism could explain such kind of dependence?
Riaz A. Khan, OK, thank you. And how this principle can explain observed concentration dependence for mixture of powder? Size of powder particles is in the range 1...10 um.
This seems to be following the Beer-Lambert Law (BLL), a too higher concentration is dampening the spectral intensity, a no go for the BLL. With more info and spectra as well as the exact method, more explanation can be looked into, including the light scattering effects.
Riaz A. Khan, thank you for your answer. I'm agree with you that absorption is one of the main processes, which plays important role. But it is at least two-folds: absorption of incident, exciting light during its penetration into powder mixture and absorption of the luminescence light during its way out of the mixture. Their interplay between each other, as well, as scattering of both above components determine observed concentration dependence.
Do you know some references deal with optical properties of powders?
Pl also check the following and the attachments. They are different than RI. Hope it provides the solution:
Journal of Optics, Volume 15, Number 3, Eshwar Thouti et al 2013 J. Opt. 15 035005
Matějec, V., Pedliková, J. & Barton, I. Optical properties of As2S3 layers deposited from solutions obtained by chemical reaction. J Sol-Gel Sci Technol 87, 696–703 (2018). https://doi.org/10.1007/s10971-018-4754-3
Scarangella A, Soumbo M, Villeneuve-Faure C, Mlayah A, Bonafos C, Monje MC, Roques C, Makasheva K. Adsorption properties of BSA and DsRed proteins deposited on thin SiO2 layers: optically non-absorbing versus absorbing proteins. Nanotechnology. 2018 Mar 16;29(11):115101. doi: 10.1088/1361-6528/aaa68b. PMID: 29318999.
Matyushkin, L. B., E-mail: [email protected], Reshetnikova, A. A., Andronov, A. O., Afonicheva, P. K., Myakin, S. V., Permiakov, N. V., and Moshnikov, V. A. Morphology, optical, and adsorption properties of copper-oxide layers deposited from complex compound solutions. United States: N. p., 2017. Web. doi:10.1134/S1063782617050165.
Journal of Applied Physics 110, 063723 (2011); https://doi.org/10.1063/1.3642965
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