Evidence for ultra-fast dissociation of molecular water from resonant Auger spectroscopy

I. Hjelte (1) , M.N. Piancastelli (2) , R. F. Fink (1) , O. Björneholm (1) , M. Bässler (2) , R. Feifel (1) , A. Giertz (1) , H. Wang (1) , K. Wiesner (1) , A. Ausmees (1) , C. Miron (2) , S.L. Sorensen (3) , S. Svensson (1)

1 Department of Physics
2 LFP - URA 2453 - Laboratoire Francis PERRIN
3 Department of Synchrotron Radiation Research

We present direct evidence for ultra-fast dissociation of molecular water in connection photo-excitation of the O1s→4a1 resonance. The core-excited H2O molecules are shown to dissociate into core-excited O*H and neutral H on a time scale comparable to the core hole lifetime, i.e. a few femtoseconds. This conclusion is based on a resonant Auger study, qualitative arguments and ab initio calculations. ‘Hot bands' connected to Auger transitions from vibrationally excited OH fragments are identified, and these exhibit a dynamical behavior which qualitatively follows the change in excess energy.

Domaines: Chimie théorique et/ou physique

I. Hjelte, M.N. Piancastelli, R. F. Fink, O. Björneholm, M. Bässler, et al.. Evidence for ultra-fast dissociation of molecular water from resonant Auger spectroscopy. Chemical Physics Letters, 2001, 334 (1-3), pp.151-158. ⟨10.1016/S0009-2614(00)01434-2⟩. ⟨hal-00144613⟩