Illuminating the Effect of the Local Environment on the Performance of Organic Sunscreens: Insights From Laser Spectroscopy of Isolated Molecules and Complexes

Sunscreens are essential for protecting the skin from UV radiation, but significant questions remain about the fundamental molecular-level processes by which they operate. In this mini review, we provide an overview of recent advanced laser spectroscopic studies that have probed how the local, chemical environment of an organic sunscreen affects its performance. We highlight experiments where UV laser spectroscopy has been performed on isolated gas-phase sunscreen molecules and complexes. These experiments reveal how pH, alkali metal cation binding, and solvation perturb the geometric and hence electronic structures of sunscreen molecules, and hence their non-radiative decay pathways. A better understanding of how these interactions impact on the performance of individual sunscreens will inform the rational design of future sunscreens and their optimum formulations.

Fluorescence lifetime of indocyanine green in molecular and nano-forms in the cellular model of a brain tumor in vitro

Any surgical intervention to a central nervous system requires special accuracy and selectivity of the effect on the cancer cells. The application of laser-spectroscopic methods provides a unique opportunity to non-invasively determine the most significant parameters that characterize the tissue states. Moreover, non-invasive state assessment of the brain tumor tissue and surrounding tissues is essential for performing a relapse-free operation. Indocyanine Green (ICG) is a photosensitizer approved for clinical practice and has absorption peak in the near-infrared range corresponding to the spectral transparency window of biological tissue. Also, the aqueous colloidal solution of ICG aggregates was used for spectroscopic properties research in glioma tumor cells. The comparative analysis of ICG in molecular and nanoforms demonstrate the difference between spectral values which allow distinguishing monomers and aggregates in tumor tissue.

H2O Collisional Broadening Coefficients at 1.37 µm and Their Temperature Dependence: A Metrology Approach

We report self- and air collisional broadening coefficients for the H2O line at 7299.43 cm−1 and corresponding temperature coefficients for a temperature range spanning 293–573 K. New laser spectroscopic setups specifically designed for this purpose have been developed and are described. The line parameters reported here are in good agreement with those values reported in the HITRAN 2020 database, but the uncertainties have been reduced by factors of about 4, 1.3 and 4.4 for the self-broadening coefficient, air broadening coefficient and the temperature exponent of air broadening, respectively. Further, we combined our measurement approach with metrological data quality objectives, addressing the traceability of the results to the international system of units (SI) and evaluated the uncertainties following the guide to the expression of uncertainty in measurement (GUM).

UVPD spectroscopy of differential mobility-selected prototropic isomers of protonated adenine

Differential mobility spectrometry is used to separate prototropic isomers of protonated adenine prior to laser spectroscopic investigation.

Laser spectroscopic and computational insights into unexpected structural behaviours of sandwich complexes on ionization

Transition-metal sandwich complexes play key roles in various fields of fundamental and applied chemistry, many of their unique properties arising from the ability to form stable or reactive ions. The...