Berlin 2014 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 12: Experimental Techniques 2
MO 12.1: Hauptvortrag
Mittwoch, 19. März 2014, 14:00–14:30, BEBEL SR144
Ultrafast X-ray Auger Probing of photoexcited molecular dynamics — B. K. McFarland1, J. Farrell1, 2, S. Miyabe1, F. Tarantelli3, A. Aguilar4, N. Berrah5, C. Bostedt6, J. D. Bozek6, P. H. Bucksbaum1,2, J. C. Castagna6, R. N. Coffee6, J. P. Cryan1,2, L. Fang5, R. Feifel7, K. J. Gaffney1, J. M. Glownia1,2, T. J. Martinez1,8, M. Mucke7, B. Murphy5, A. Natan1, T. Osipov5, V. S. Petrovic1,2, S. Schorb6, Th. Schultz9, L. S. Spector1,2, M. Swiggers6, I. Tenney1,2, S. Wang1,2, J. L. White1,2, W. White6, and •M. Guehr1,2 — 1PULSE, SLAC, Menlo Park, USA — 2Physics/Applied Physics, Stanford Univ., Stanford, USA — 3Chemistry, Univ. Perugia, and ISTM-CNR, Perugia, Italy — 4ALS, LBNL, Berkeley, USA — 5Physics, WMU., Kalamazoo, USA — 6LCLS, SLAC Menlo Park, USA — 7Physics/Astronomy, Uppsala Univ., Uppsala, Sweden — 8Chemistry, Stanford Univ., Stanford, USA — 9Max-Born-Institut, Berlin, Germany
Molecules efficiently and selectively convert light energy into other energy forms through ultrafast nuclear and electronic rearrangements. Efforts to distinguish the role of nuclear and electronic dynamics remain challenging. We performed femtosecond ultraviolet pump - x-ray Auger probe spectroscopy at the linac coherent light source (LCLS). This method can be used to separate electronic and nuclear relaxation in photoexcited molecular dynamics and we address the UV photoprotection mechanism of isolated nucleobases. We find a very fast electronic relaxation within 200 fs after excitation, which cannot be described within the Born-Oppenheimer approximation.