Linear optical spectroscopy (absorption, fluorescence, etc.) is a powerful tool that is used as the first mode of investigation in many physics, chemistry, and biology laboratories. Nevertheless, a good conceptual understanding of the underlying physics taking place during optical measurements—the absorption of light and the subsequent molecular response—is often lacking for researchers who use these techniques. In this talk, I will first provide a conceptual description of the physics underlying optical spectroscopy, considering a photosynthetic light-harvesting complex as a model system. I will then discuss the basics of spectral modelling by considering a common cumulant expansion-based simulation method and, finally, describe a spectroscopic method called surface plasmon resonance (SPR) and discuss how it can be improved by the use of quantum light.
The physics of linear optical spectroscopy: a conceptual description
Abstract
Speaker
Dr Towan Nöthling
Department of Physics, University of Pretoria
About (click to open/close)
Dr Towan Nöthling completed his PhD in biophysics in 2023 under the supervision of Prof. Tjaart Krüger in the Department of Physics at the University of Pretoria. He is currently employed as a postdoctoral fellow in the same research group, where his main focus is the simulation of optical spectroscopic results and the development of new optical spectroscopic methods. His most recent work involves the assembly of a quantum surface plasmon resonance (qSPR) experimental setup that will be used to investigate the molecular interaction between plant pathogens and host immune cells in order to develop early disease detection in economically important plant species. Dr Nöthling has co-authored nine publications, including a book chapter on the quantum aspects of photosynthetic spectral modelling, and has presented several national and international conference talks.
Selected publications (click to open/close)
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1.
Nöthling JA, Mančal T, Krüger TPJ. Accuracy of approximate methods for the calculation of fluorescence-type linear spectra with a complex system–bath coupling. J Chem Phys [Internet]. 2025 Jan 8 [cited 2026 Oct 27];162(2):024102. Available from: https://doi.org/10.1063/5.0242756 Cite
1.
Nöthling JA, Mančal T, Krüger TPJ. Accuracy of approximate methods for the calculation of absorption-type linear spectra with a complex system–bath coupling. J Chem Phys [Internet]. 2022 Sept 7 [cited 2026 Oct 27];157(9):095103. Available from: https://doi.org/10.1063/5.0100977 Cite
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