TY  - JOUR
A1  - Mayer, Dennis
A1  - Lever, Fabiano
A1  - Gühr, Markus
T1  - Data analysis procedures for time-resolved x-ray photoelectron spectroscopy at a SASE free-electron-laser
JF  - Journal of physics : B, Atomic, molecular and optical physics
N2  - The random nature of self-amplified spontaneous emission (SASE) is a well-known challenge for x-ray core level spectroscopy at SASE free-electron lasers (FELs). Especially in time-resolved experiments that require a combination of good temporal and spectral resolution the jitter and drifts in the spectral characteristics, relative arrival time as well as power fluctuations can smear out spectral-temporal features. We present a combination of methods for the analysis of time-resolved photoelectron spectra based on power and time corrections as well as self-referencing of a strong photoelectron line. Based on sulfur 2p photoelectron spectra of 2-thiouracil taken at the SASE FEL FLASH2, we show that it is possible to correct for some of the photon energy drift and jitter even when reliable shot-to-shot photon energy data is not available. The quality of pump-probe difference spectra improves as random jumps in energy between delay points reduce significantly. The data analysis allows to identify coherent oscillations of 1 eV shift on the mean photoelectron line of 4 eV width with an error of less than 0.1 eV.
KW  - free-electron laser
KW  - photoelectron spectroscopy
KW  - FLASH
Y1  - 2022
U6  - https://doi.org/10.1088/1361-6455/ac3c91
SN  - 0953-4075
SN  - 1361-6455
VL  - 55
IS  - 5
PB  - IOP Publ.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Lever, Fabiano
A1  - Mayer, Dennis
A1  - Metje, Jan
A1  - Alisauskas, Skirmantas
A1  - Calegari, Francesca
A1  - Düsterer, Stefan
A1  - Feifel, Raimund
A1  - Niebuhr, Mario
A1  - Manschwetus, Bastian
A1  - Kuhlmann, Marion
A1  - Mazza, Tommaso
A1  - Robinson, Matthew Scott
A1  - Squibb, Richard J.
A1  - Trabattoni, Andrea
A1  - Wallner, Måns
A1  - Wolf, Thomas J. A.
A1  - Gühr, Markus
T1  - Core-level spectroscopy of 2-thiouracil at the sulfur L1 and L2,3 edges utilizing a SASE free-electron-laser
JF  - Molecules
N2  - 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.
KW  - X-ray
KW  - photoelectron
KW  - sulfur
KW  - thiouracil
KW  - nucleobases
KW  - Coster–Kronig
KW  - Auger–Meitner
KW  - NEXAFS
KW  - FLASH
Y1  - 2021
SN  - 1420-3049
VL  - 26
IS  - 21
PB  - MDPI
CY  - Basel
ER  -