title: Optical Fluorescence Detected from X-ray Irradiated Liquid Water.
abstract: Despite its importance, the structure and dynamics of liquid water are still poorly understood in many apsects. Here, we report on the observation of optical fluorescence upon soft X-ray irradiation of liquid water. Detection of spectrally resolved fluorescence was achieved by a combination of the liquid microjet technique and fluorescence spectroscopy. We observe a genuine liquid-phase fluorescence manifested by a broad emission band in the 170-340 nm (4-7 eV) photon wavelength range. In addition, another narrower emission near 300 nm can be assigned to the fluorescence of OH (A state) in the gas phase, the emitting species being formed by Auger electrons escaping from liquid water. We argue that the newly observed broad-band emission of liquid water is relevant in search of extraterrestrial life, and we also envision the observed electron-ejection mechanism to find application for exploring solutes at liquid-vapor interfaces.
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hans
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Ozga
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Seidel
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Schmidt
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Ueltzhöffer
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Xaver
authors.initials: X
authors.lastname: Holzapfel
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Philip
authors.initials: P
authors.lastname: Wenzel
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Reiß
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.|Department of Physics, Free University Berlin , Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: Marvin N
authors.initials: MN
authors.lastname: Pohl
authors.affiliation: Department of Physics and Astronomy, Uppsala University , Box 516, SE-75120 Uppsala, Sweden.
authors.forename: Isaak
authors.initials: I
authors.lastname: Unger
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.|Department of Physics, Free University Berlin , Arnimallee 14, D-14195 Berlin, Germany.|School of Chemistry, Monash University , Clayton Campus, Victoria 3800, Australia.
authors.forename: Emad F
authors.initials: EF
authors.lastname: Aziz
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Ehresmann
authors.affiliation: Department of Physical Chemistry, University of Chemistry and Technology Prague , Technická 5, 16628 Prague, Czech Republic.
authors.forename: Petr
authors.identifier: 0000-0002-5358-5538
authors.initials: P
authors.lastname: Slavíček
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Winter
authors.affiliation: University of Kassel and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT) , Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Knie