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 is directly observed and absolute emission cross sections were determined. For resonant innershell excitations, the fluorescing excited hydrogen state is found to be strongly dependent on the molecular or Rydberg-like character of the excitation.

Real-Time Dynamics of the Formation of Hydrated Electrons upon Irradiation of Water Clusters with Extreme Ultraviolet Light

“…In general, there are three ways to create excited hydrogen atoms with XUV radiation. The first option is dissociative photoexcitation of H 2 O into OH and H Ã ðn ¼ 2Þ which has been reported for molecular water [36], but this is only a minor contribution in our experiment due to the low cross section [37]. A second option is the direct recombination of quasi-free electrons with H þ after photodissociation of H 2 O into OH − and H þ .…”

Extreme Ultraviolet to Visible Dispersed Single Photon Detection for Highly Sensitive Sensing of Fundamental Processes in Diverse Samples

“…The photodissociation of small molecules has been investigated extensively over the past decades by photon-induced fluorescence spectroscopy, focusing mostly on gaseous di- and triatomic species like H 2 [ 33 ], N 2 [ 34 ], O 2 , NO [ 23 ], N 2 O [ 35 ], and CO [ 26 ]. More recently, we determined the absolute production probability of excited hydrogen fragments after valence photoexcitation of the water molecule H 2 O [ 36 ]. The main result of this work is shown in Figure 7 .…”

“… Absolute emission cross section of single transitions of the Lyman series emitted by neutral hydrogen fragments after photodissociation of valence excited water molecules (data taken from [ 36 ]). ( a ) 2D colormap of the emission intensity of the Lyman transitions as function of the exciting photon energy; ( b ) absolute emission cross section of the transitions to as function of the exciting photon energy.…”

Optical Fluorescence Detected from X-ray Irradiated Liquid Water

“…However, the overall shape resembles the well known excitation function of emission from gas-phase water 21,22 and three characteristic peaks at about 534.0 eV, 535.9 eV, and 537.1 eV can clearly be assigned to inner-shell excitations in molecular water. 45 Feature I must hence be arising from the excitation of gas-phase water molecules at very close distance from the liquid jet.…”