Observation of the molecular response to light upon photoexcitation

Haiwang Yong, Nikola Zotev, Jennifer M. Ruddock, Brian Stankus, Mats Simmermacher, Andrés Moreno Carrascosa, Wenpeng Du, Nathan Goff, Yu Chang, Darren Bellshaw, Mengning Liang, Sergio Carbajo, Jason E. Koglin, Joseph S. Robinson, Sébastien Boutet, Michael P. Minitti, Adam Kirrander, Peter M. Weber*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


When a molecule interacts with light, its electrons can absorb energy from the electromagnetic field by rapidly rearranging their positions. This constitutes the first step of photochemical and photophysical processes that include primary events in human vision and photosynthesis. Here, we report the direct measurement of the initial redistribution of electron density when the molecule 1,3-cyclohexadiene (CHD) is optically excited. Our experiments exploit the intense, ultrashort hard x-ray pulses of the Linac Coherent Light Source (LCLS) to map the change in electron density using ultrafast x-ray scattering. The nature of the excited electronic state is identified with excellent spatial resolution and in good agreement with theoretical predictions. The excited state electron density distributions are thus amenable to direct experimental observation.

Original languageEnglish
Article number2157
Number of pages6
JournalNature Communications
Early online date1 May 2020
Publication statusPublished - 1 May 2020


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