Electron-impact ionization of the water molecule at large momentum transfer above the double-ionization threshold

Abstract

The single and double ionization of the water molecule at large momentum transfer has been studied using a combination of (e,2e) and (e,3-1e) spectroscopy, with the binding energy spectrum being measured from 0 to 100 eV. The experiment has been performed in the symmetric noncoplanar geometry at an incident electron energy of 2055 eV. In this way we have achieved a large momentum transfer of 9 a.u. In particular, we present an observation of a relatively intense band at around 58 eV. Symmetry-adapted cluster configuration interaction (SAC-CI) general-R calculations for single ionization indicate that the observed band is at least partly generated by a cluster of satellites with small intensities, which predominantly belong to states possessing 2 A 1 symmetry originating from the mixing of the (2a 1 ) −1 state with two electron processes. Nevertheless, it has been found that the entire spectrum above the lowest double-ionization threshold cannot be understood, even qualitatively, with the SAC-CI calculations. This result suggests that the (e,3-1e) double-ionization processes have a significant contribution to the observations.

Triple differential cross-section for the twisted electron impact ionization of water molecule

“…Different other models, like 1CW (analytical expression) [16,17], generalised Sturmian function (GSF) [18], two molecular three-body distorted wave approach (M3DW) [19], multicenter three distorted waves (MCTDW) [20], second-order distorted wave Born approximation (DWBA2) [21], have also been used. In addition to (e,2e) processes, various theoretical (e,3e) investigations have been done to study the double ionization on H 2 O [22][23][24].…”

Outer- and inner-valence satellites of carbon dioxide: Electron momentum spectroscopy compared with symmetry-adapted-cluster configuration interaction general-R calculations

“…The sudden approximation involving single-step one electron process cannot be used to explain a large number of ionization bands observed in the innervalence range and even in the outer-valence range. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The ejected electron changes the potential for valence electrons and one or more valence electrons may be excited or ionized simultaneously. This process due to electron correlation effect is known as shake-up or shake-off process.…”

“…[17][18][19] have exhibited its potential in observing the low-intensity closely spaced shake-up states. 7,8,14,15 On the theoretical side, highly accurate SAC-CI (symmetryadapted-cluster configuration interaction) general-R method has achieved "fine theoretical spectroscopy" for the ionization of a series of molecules. [20][21][22][23][24][25][26] Carbon dioxide, which has considerable fundamental as well as applied interests, has been extensively studied by means of various experimental techniques and theoretical calculations.…”

Investigation of Ionization Potential in Quantum Dots Using the Stratified Stochastic Enumeration of Molecular Orbitals Method

“…This process is called interatomic Coulombic decay (ICD). , The IPs of both the inner and outer orbitals of molecules, dimers, and clusters influence which de-excitation mechanism occurs in a highly excited neutral or a highly excited ionized state of these types of systems. Knowledge of the IPs of these systems’ inner and outer orbitals can assist in the prediction of which de-excitation mechanism is likely to occur in a system of interest. − High precision IP measurements in atoms and molecules provide important information about electron–electron correlation and serves as a benchmark for the development and testing of theories. Ionization potential also is a quantity of interest in biological systems.…”