Observation of intermolecular Coulombic decay and shake-up satellites in liquid ammonia

0559973 - ÚOCHB 2023 RIV US eng J - Journal Article
Schewe, Hanns Christian - Muchová, E. - Bělina, M. - Buttersack, T. - Stemer, D. - Seidel, R. - Thürmer, S. - Slavíček, P. - Winter, B.
Observation of intermolecular Coulombic decay and shake-up satellites in liquid ammonia.
Structural Dynamics. Roč. 9, č. 4 (2022), č. článku 044901. E-ISSN 2329-7778
Institutional support: RVO:61388963
Keywords : Auger electron spectrum * neutron diffraction * ab initio
OECD category: Physical chemistry
Impact factor: 2.8, year: 2022
Method of publishing: Open access
https://doi.org/10.1063/4.0000151

We report the first nitrogen 1s Auger-Meitner electron spectrum from a liquid ammonia microjet at a temperature of ∼223 K (-50 °C) and compare it with the simultaneously measured spectrum for gas-phase ammonia. The spectra from both phases are interpreted with the assistance of high-level electronic structure and ab initio molecular dynamics calculations. In addition to the regular Auger-Meitner-electron features, we observe electron emission at kinetic energies of 374-388 eV, above the leading Auger-Meitner peak (3a12). Based on the electronic structure calculations, we assign this peak to a shake-up satellite in the gas phase, i.e., Auger-Meitner emission from an intermediate state with additional valence excitation present. The high-energy contribution is significantly enhanced in the liquid phase. We consider various mechanisms contributing to this feature. First, in analogy with other hydrogen-bonded liquids (noticeably water), the high-energy signal may be a signature for an ultrafast proton transfer taking place before the electronic decay (proton transfer mediated charge separation). The ab initio dynamical calculations show, however, that such a process is much slower than electronic decay and is, thus, very unlikely. Next, we consider a non-local version of the Auger-Meitner decay, the Intermolecular Coulombic Decay. The electronic structure calculations support an important contribution of this purely electronic mechanism. Finally, we discuss a non-local enhancement of the shake-up processes.
Permanent Link: https://hdl.handle.net/11104/0333082