Beyond Beer’s Law: Quasi-Ideal Binary Liquid Mixtures

Mayerhoefer TG, Ilchenko O, Kutsyk A, Popp J (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Applied Spectroscopy Optical Society of America / Society for Applied Spectroscopy

Book Volume: 76

Pages Range: 92-104

Journal Issue: 1

DOI: 10.1177/00037028211056293

Abstract

We have recorded attenuated total reflection infrared spectra of binary mixtures in the (quasi-)ideal systems benzene–toluene, benzene–carbon tetrachloride, and benzene–cyclohexane. We used two-dimensional correlation spectroscopy, principal component analysis, and multivariate curve resolution to analyze the data. The 2D correlation proves nonlinearities, also in spectral ranges with no obvious deviations from Beer’s approximation. The number of principal components is much higher than two and multivariate curve resolution carried out under the assumption of the presence of a third component, results in spectra which only show bands of the original components. The results negate the presence of third components, since any complex should have lower symmetry than the individual molecules and thus more and/or different infrared-active bands in the spectra. Based on Lorentz–Lorenz theory and literature values of the optical constants, we show that the nonlinearities and additional principal components are consequences of local field effects and the polarization of matter by light. Lorentz–Lorenz theory is, however, not able to explain, for example, the different blueshifts of the strong A2u band of benzene in the three mixtures. Obviously, infrared spectroscopy is sensitive to the short-range order around the molecules, which changes with content, their shapes, and their anisotropy. (Figure presented.).

Involved external institutions

Leibniz-Institut für Photonische Technologien e.V. DE Germany (DE) Technical University of Denmark / Danmarks Tekniske Universitet (DTU) DK Denmark (DK) Taras Shevchenko National University of Kyiv (KNU) / Київський національний університет імені Тараса Шевченка UA Ukraine (UA)

How to cite

APA:

Mayerhoefer, T.G., Ilchenko, O., Kutsyk, A., & Popp, J. (2022). Beyond Beer’s Law: Quasi-Ideal Binary Liquid Mixtures. Applied Spectroscopy, 76(1), 92-104. https://dx.doi.org/10.1177/00037028211056293

MLA:

Mayerhoefer, Thomas G., et al. "Beyond Beer’s Law: Quasi-Ideal Binary Liquid Mixtures." Applied Spectroscopy 76.1 (2022): 92-104.

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