Photoelectron spectroscopy of large water clusters ionized by an XUV comb

Andrea Trabattoni,Qingcao Liu,Krishna Saraswathula,Lennart Seiffert,Philipp Rupp,Loren Ban,Lorenzo Colaizzi,Matthias F Kling,Francesca Calegari,Vincent Wanie,Andrea Cartella,Erik P Månsson,Thomas Fennel,Ruth Signorell,François Légaré,Bruce L Yoder,Elisabeth A Herzig

doi:10.1088/2515-7647/ab92b1

Abstract

Detailed knowledge about photo-induced electron dynamics in water is key to the understanding of several biological and chemical mechanisms, in particular for those resulting from ionizing radiation. Here we report a method to obtain photoelectron spectra from neutral water clusters following ionization by an extreme-ultraviolet (XUV) attosecond pulse train, representing a first step towards a time-resolved analysis. Typically, a large background signal in the experiment arises from water monomers and carrier gas used in the cluster source. We report a protocol to quantify this background in order to eliminate it from the experimental spectra. We disentangle the accumulated XUV photoionization signal into contributions from the background species and the photoelectron spectra from the clusters. This proof-of-principle study demonstrates feasibility of background free photoelectron spectra of neutral water clusters ionized by XUV combs and paves the way for the detailed time-resolved analysis of the underlying dynamics.

Highlights

A detailed understanding of electron scattering properties in water is crucial to modeling and controlling many processes occurring in nature, ranging from atmospheric chemistry to radiation biology [1,2,3]
To have a more accurate picture of the photoelectron distributions produced for the three target conditions described above, the full three-dimensional momentum spheres were retrieved by Abel inversion of the 2D projected data of figures 1(b)–(d) on a basis of Legendre polynomials, using the BASEX method [29].the corresponding center-slices of the reconstructed photoelectron distributions were angularly integrated, and the resulting curves were plotted in figure 2(a) as a function of the photoelectron energy for He, He/monomer and clusters
In this work we reported a photoelectron spectroscopy experiment on neutral water clusters ionized by a high harmonic comb in the XUV

Summary

Introduction

A detailed understanding of electron scattering properties in water is crucial to modeling and controlling many processes occurring in nature, ranging from atmospheric chemistry to radiation biology [1,2,3]. When highly energetic radiation interacts with biological tissue, for example, an ionization track leads to the formation of many intermediate species, eventually breaking down the tissue into smaller products. During this process, low-energy electrons (kinetic energies between 10 and 50 eV) have been shown to play a central role in DNA damage [4,5,6]. The only available data on electron scattering cross sections in the 10–50 eV energy range is for amorphous ice [13]. Electron scattering in large neutral water clusters (H2O)n was investigated and compared to condensed-phase data [14, 15]

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Discussion

Conclusion