Lyman-series emission after valence and core excitation of water vapor

Abstract

We report Lyman-series emission cross sections of neutral hydrogen dissociation fragments after valence (15--34 eV) and inner-shell (533--542 eV) excitation of water vapor with monochromatic synchrotron radiation as functions of the exciting-photon energy. In the valence excitation energy region, the thermodynamical limits of the production of the differently excited hydrogen fragments are directly observed and absolute emission cross sections are determined. For resonant inner-shell excitations, the fluorescing excited hydrogen state is found to be strongly dependent on the molecular or Rydberg-like character of the excitation.