TY  - JOUR
A1  - Johansson, Fredrik O. L.
A1  - Leitner, Torsten
A1  - Bidermane, Ieva
A1  - Born, Artur
A1  - Föhlisch, Alexander
A1  - Svensson, Svante
A1  - Mårtensson, Nils
A1  - Lindblad, Andreas
T1  - Auger- and photoelectron coincidences of molecular O2 adsorbed on Ag(111)
JF  - Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy
N2  - The oxygen on Ag(111) system has been investigated with Auger electron-photoelectron coincidence spectroscopy (APECS). 
The coincidence spectra between O 1s core level photoelectrons and O KLL Auger electrons have been studied together with Ag(3)d/AgM4,5NN coincidences. 
We also describe the electron-electron coincidence spectrometer setup, CoESCA, consisting of two angle resolved time-of-flight spectrometers at a synchrotron light source. 
Contributions from molecular oxygen and chemisorbed oxygen are assigned using the coincidence data, conclusions are drawn primarily from the O 1s/O KLL data. 
The data acquisition and treatment procedure are also outlined. 
The chemisorbed oxygen species observed are relevant for the catalytic ethylene oxidation.
KW  - oxygen/Ag(111)
KW  - Auger electron
KW  - photoelectron
KW  - coincidence
KW  - APECS
KW  - spectroscopy
Y1  - 2022
U6  - https://doi.org/10.1016/j.elspec.2022.147174
SN  - 0368-2048
SN  - 1873-2526
VL  - 256
PB  - Elsevier
CY  - New York, NY [u.a.]
ER  - 
TY  - JOUR
A1  - Giangrisostomi, Erika
A1  - Ovsyannikov, Ruslan
A1  - Sorgenfrei, Florian
A1  - Zhang, Teng
A1  - Lindblad, Andreas
A1  - Sassa, Yasmine
A1  - Cappel, Ute B.
A1  - Leitner, Torsten
A1  - Mitzner, Rolf
A1  - Svensson, Svante
A1  - Martensson, Nils
A1  - Föhlisch, Alexander
T1  - Low Dose Photoelectron Spectroscopy at BESSY II
BT  - electronic structure of matter in its native state
JF  - Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy
N2  - The implementation of a high-transmission, angular-resolved time-of-Right electron spectrometer with a 1.25 MHz pulse selector at the PM4 soft X-ray dipole beamline of the synchrotron BESSY II creates unique capabilities to inquire electronic structure via photoelectron spectroscopy with a minimum of radiation dose. Solid-state samples can be prepared and characterized with standard UHV techniques and rapidly transferred from various preparation chambers to a 4-axis temperature-controlled measurement stage. A synchronized MHz laser system enables excited-state characterization and dynamical studies starting from the picosecond timescale. This article introduces the principal characteristics of the PM4 beamline and LowDosePES end-station. Recent results from graphene, an organic hole transport material for solar cells and the transition metal dichalcogenide MoS2 are presented to demonstrate the instrument performances.
Y1  - 2018
U6  - https://doi.org/10.1016/j.elspec.2017.05.011
SN  - 0368-2048
SN  - 1873-2526
VL  - 224
SP  - 68
EP  - 78
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Cappel, Ute B.
A1  - Svanstrom, Sebastian
A1  - Lanzilotto, Valeria
A1  - Johansson, Fredrik O. L.
A1  - Aitola, Kerttu
A1  - Philippe, Bertrand
A1  - Giangrisostomi, Erika
A1  - Ovsyannikov, Ruslan
A1  - Leitner, Torsten
A1  - Föhlisch, Alexander
A1  - Svensson, Svante
A1  - Martensson, Nils
A1  - Boschloo, Gerrit
A1  - Lindblad, Andreas
A1  - Rensmo, Hakan
T1  - Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells
JF  - ACS applied materials & interfaces
N2  - Metal halide perovskites have emerged as materials of high interest for solar energy-to-electricity conversion, and in particular, the use of mixed-ion structures has led to high power conversion efficiencies and improved stability. For this reason, it is important to develop means to obtain atomic level understanding of the photoinduced behavior of these materials including processes such as photoinduced phase separation and ion migration. In this paper, we implement a new methodology combining visible laser illumination of a mixed-ion perovskite ((FAP-bI(3))(0.85)(MAPbBr(3))(0.15)) with the element specificity and chemical sensitivity of core-level photoelectron spectroscopy. By carrying out measurements at a synchrotron beamline optimized for low X-ray fluxes, we are able to avoid sample changes due to X-ray illumination and are therefore able to monitor what sample changes are induced by visible illumination only. We find that laser illumination causes partially reversible chemistry in the surface region, including enrichment of bromide at the surface, which could be related to a phase separation into bromide- and iodide-rich phases. We also observe a partially reversible formation of metallic lead in the perovskite structure. These processes occur on the time scale of minutes during illumination. The presented methodology has a large potential for understanding light-induced chemistry in photoactive materials and could specifically be extended to systematically study the impact of morphology and composition on the photostability of metal halide perovskites.
KW  - photoelectron spectroscopy
KW  - laser illumination
KW  - lead halide perovskite
KW  - ion migration
KW  - phase separation
KW  - stability
Y1  - 2017
U6  - https://doi.org/10.1021/acsami.7b10643
SN  - 1944-8244
VL  - 9
SP  - 34970
EP  - 34978
PB  - American Chemical Society
CY  - Washington
ER  -