# Ultrafast Spectroscopy of Commercial Sunscreen Formulations in Thin Films and on a Skin Mimic

## TL;DR

This study shows that the basic light behavior of sunscreen ingredients is similar in pure form and in real products, even on a skin-like surface.

## Contribution

Demonstrates that fundamental spectroscopic behavior of UV filters is preserved in formulations and on skin mimics.

## Key findings

- Ultrafast spectroscopy reveals similar photodynamics of UV filters in pure and formulated states.
- Sunscreen ingredients interact similarly in formulations as in isolated conditions.
- Findings validate the relevance of fundamental spectroscopy for real-world applications.

## Abstract

The photodynamics of a given chromophore are usually
affected by
the surrounding environment (e.g., solvent or matrix). As a result,
it is often assumed that the ‘fundamental’ spectroscopic
behavior of a given chromophore, usually studied in dilute solution,
is not relevant to the understanding of more complex mixtures. In
this work, we demonstrate that the ‘fundamental’ photodynamics
of common sunscreen UV filters are comparable to those observed in
formulation, including the complex interactions between them, and
even for formulation applied to a skin mimic. In particular, we have
carried out ultrafast laser spectroscopy studies directly on sunscreen
formulations containing methyl anthranilate (MA), ethylhexyl methoxycinnamate
(EHMC), and octocrylene (OCR) as commonly used UV filters. Our results
not only have significant implications for the sunscreen industry,
providing direct evidence of UV filter interactions in formulation,
but importantly they are demonstrative of the relevance of ‘fundamental’
spectroscopic techniques to understanding real-life systems.