Core-Level Spectroscopy of 2-Thiouracil at the Sulfur L1- and L2,3-Edges Utilizing a SASE Free-Electron Laser.

Fabiano Lever,Skirmantas Alisauskas,Francesca Calegari,Måns Wallner,Markus Gühr,Tommaso Mazza,Dennis Mayer,Andrea Trabattoni,Mario Niebuhr,Marion Kuhlmann,Thomas J A Wolf,Matthew Scott Robinson,Raimund Feifel,Stefan Düsterer,Jan Metje,Bastian Manschwetus,Richard J Squibb

doi:10.3390/molecules26216469

Abstract

In this paper, we report X-ray absorption and core-level electron spectra of the nucleobase derivative 2-thiouracil at the sulfur L1- and L2,3-edges. We used soft X-rays from the free-electron laser FLASH2 for the excitation of isolated molecules and dispersed the outgoing electrons with a magnetic bottle spectrometer. We identified photoelectrons from the 2p core orbital, accompanied by an electron correlation satellite, as well as resonant and non-resonant Coster–Kronig and Auger–Meitner emission at the L1- and L2,3-edges, respectively. We used the electron yield to construct X-ray absorption spectra at the two edges. The experimental data obtained are put in the context of the literature currently available on sulfur core-level and 2-thiouracil spectroscopy.

Highlights

Spectroscopy of 2-Thiouracil at the Sulfur L1 - and L2,3 -Edges Utilizing a spontaneous emission (SASE) Free-Electron Laser
We present a static X-ray spectroscopic study of 2-tUra performed at the sulfur L-edge
The free-electron laser (FEL) photon energy hυ was scanned over the ionization edge region from hυ = 155 to 175 eV, with 0.75 eV steps in randomized order; the averaged FEL bandwidth was about 4 eV

Summary

Introduction

Spectroscopy of 2-Thiouracil at the Sulfur L1 - and L2,3 -Edges Utilizing a SASE Free-Electron Laser. We report X-ray absorption and core-level electron spectra of the nucleobase derivative 2-thiouracil at the sulfur L1 - and L2,3 -edges. 1. Introduction with regard to jurisdictional claims in Recent years have seen increasing interest in the study of sulfur-substituted nucleobases, known as thionucleobases, for applications in medicine and biochemistry [1,2]. Introduction with regard to jurisdictional claims in Recent years have seen increasing interest in the study of sulfur-substituted nucleobases, known as thionucleobases, for applications in medicine and biochemistry [1,2] They differ from their canonical counterparts in their response to UV radiation. Their reactive triplet state makes thionucleobases useful as cross-linking agents [9,10], as well as candidates for photoinduced cancer treatment [11,12]

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Conclusion