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 T2 - 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 UR - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/37887 SN - 2041-1723 VL - 5 PB - Nature Publ. Group CY - London ER -