Regensburg 2025 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 100: Focus Session Chemical Imaging for the Elucidation of Molecular Structure II (joint session O/BP)
O 100.7: Talk
Friday, March 21, 2025, 12:30–12:45, H24
Domain size effects in the spectra of micro-heterogeneous samples — •Thomas Mayerhöfer1,2 and Jürgen Popp1,2 — 1Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany — 2Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4, 07743 Jena, Germany
Samples are often not composed of a single pure compound but are instead mixtures of different substances. Under the Bouguer-Beer-Lambert approximation, the absorbance spectra of such mixtures can be simply derived by summing the spectra of the individual components, with each spectrum weighted by the molar fraction of the corresponding compound.
In the context of wave optics, the resolving power of light at a given wavelength becomes crucial. If a microscope using light at this wavelength can distinguish structural details within the sample, the sample is classified as micro-heterogeneous. In this case, spatial averaging occurs at the intensity level, involving reflectance and transmittance rather than absorbance.
The shift from micro-heterogeneity to macro-heterogeneity is gradual and cannot be described by an analytical formula due to the wave nature of light. This has significant implications for spectrum interpretation, as it can lead to substantial variations in peak shapes, positions, and intensities, e.g., during mitosis.
Keywords: domain size effect; micro-heterogeneous mixtures; spatial averaging of spectra