TY  - JOUR
A1  - Holldack, Karsten
A1  - Ovsyannikov, Ruslan
A1  - Kuske, P.
A1  - Mueller, R.
A1  - Schaelicke, A.
A1  - Scheer, M.
A1  - Gorgoi, Mihaela
A1  - Kuehn, D.
A1  - Leitner, T.
A1  - Svensson, S.
A1  - Martensson, N.
A1  - Föhlisch, Alexander
T1  - Single bunch X-ray pulses on demand from a multi-bunch synchrotron radiation source
JF  - Nature Communications
N2  - Synchrotron radiation facilities routinely operate in a multi-bunch regime, but applications relying on time-of-flight schemes require single bunch operation. Here we show that pulse picking by resonant excitation in a storage ring creates in addition to the multi-bunch operation a distinct and separable single bunch soft X-ray source. It has variable polarization, a photon flux of up to 10(7)-10(9) ph s(-1)/0.1%BW at purity values of 10(4)-10(2) and a repetition rate of 1.25 MHz. The quasi-resonant excitation of incoherent betatron oscillations of electrons allows horizontal pulse separation at variable (also circular) polarization accessible for both, regular 30 ps pulses and ultrashort pulses of 2-3 ps duration. Combined with a new generation of angularly resolving electron spectrometers this creates unique opportunities for time-resolved photoemission studies as confirmed by time-of-flight spectra. Our pulse picking scheme is particularly suited for surface physics at diffraction-limited light sources promising ultimate spectral resolution.
Y1  - 2014
U6  - https://doi.org/10.1038/ncomms5010
SN  - 2041-1723
VL  - 5
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Ovsyannikov, Ruslan
A1  - Karlsson, P.
A1  - Lundqvist, M.
A1  - Lupulescu, C.
A1  - Eberhardt, W.
A1  - Föhlisch, Alexander
A1  - Svensson, S.
A1  - Martensson, N.
T1  - Principles and operation of a new type of electron spectrometer - ArTOF
JF  - Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy
N2  - A new energy and angular electron analyzer ArTOF (Angular Resolved Time of Flight) is described. The analyzer is based on simultaneous measurement of flight times and angles in an advanced electron lens system. In angular modes the new analyzer combines an increase in transmission by almost three orders of magnitude with improved resolution, in comparison to standard state-of-the-art electron spectrometers. In this report we describe some design principles and we give a review of calibration and alignment procedures necessary for the use of the ArTOF on a synchrotron radiation facility. Our program scripts to handle the large datasets are also discussed. Furthermore we give a broad description of the new research fields that benefit from the use of the ArTOF and give a short summary of the first results of angle resolved photoemission measurement with ArTOF using the single-bunch X-ray pulses from the BESSY II storage ring facility. (C) 2013 Published by Elsevier B.V.
KW  - ARPES
KW  - Time of flight
KW  - Synchrotron
KW  - Electron spectroscopy
Y1  - 2013
U6  - https://doi.org/10.1016/j.elspec.2013.08.005
SN  - 0368-2048
SN  - 1873-2526
VL  - 191
IS  - 12
SP  - 92
EP  - 103
PB  - Elsevier
CY  - Amsterdam
ER  -