Photophysics of indole upon X-ray absorption published in PCCP

20 July, 2018

We have recently published experimental results on the "Photophysics of indole upon X-ray absorption“ in the journal of Physical Chemistry, Chemistry Physics.

Indole is the chromophore of the essential amino acid tryptophan. It is an ubiquitous part of peptides and proteins, and is frequently the focus of theoretical and experimental publication, including cluster and deflection experiments published by the CMI group in 2012 and 2018.

In this most recent publication we focus on the relaxation dynamics of indole upon single-photon x-ray absorption. After innershell photoionization, biomolecules can relax via Auger decay, which typically leads to the Coulomb explosion of the molecules. The emitted photo- and Auger electrons as well as the ionic fragments of indole were measured in coincidence with a double-sided velocity-map-imaging spectrometer. This spectrometer made it possible to measure the 3D (2D) momentum of the ionic fragments (electron), and, therefore, allowed to measure the products following the relaxation process in great detail. We presented the complex ionic fragmentation pattern of indole and analyzed the corresponding electron signal. We showed the angular relationship between ionic fragments and discussed, amongst others, the influence of site-specific ionization on the molecular fragmentation pattern.

This experiment was conducted at the P04 beamline at Petra III and is the first publication of the CMI group along a series of experiments conducted with synchrotron radiation. The team was lead by Dr. Sebastian Trippel, and was working in close collaboration with the groups headed by Daniel Rolles (now Kansas State University) and Jens Viefhaus (now Helmholtz-Zentrum Berlin).