title: Analysis of the Electronic Structure of Aqueous Urea and Its Derivatives: A Systematic Soft X-Ray-TD-DFT Approach.
abstract: Soft X-ray emission (XE), absorption (XA), and resonant inelastic scattering (RIXS) experiments have been conducted at the nitrogen K-edge of urea and its derivatives in aqueous solution and were compared with density functional theory and time-dependent density functional theory calculations. This comprehensive study provides detailed information on the occupied and unoccupied molecular orbitals of urea, thiourea, acetamide, dimethylurea, and biuret at valence levels. By identifying the electronic transitions that contribute to the experimental spectral features, the energy gap between the highest occupied and the lowest unoccupied molecular orbital of each molecule is determined. Moreover, a theoretical approach is introduced to simulate resonant inelastic X-ray scattering spectra by adding an extra electron to the lowest unoccupied molecular orbital, thereby mimicking the real initial state of the core-electron absorption before the subsequent relaxation process.
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany. marc.tesch@helmholtz-berlin.de.
authors.forename: Marc F
authors.initials: MF
authors.lastname: Tesch
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany.|Department of Chemistry, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany.
authors.forename: Ronny
authors.initials: R
authors.lastname: Golnak
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Ehrhard
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany.|Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Schön
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany.
authors.forename: Jie
authors.initials: J
authors.lastname: Xiao
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany.|Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
authors.forename: Kaan
authors.initials: K
authors.lastname: Atak
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Bande
authors.affiliation: Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489, Berlin, Germany. emad.aziz@helmholtz-berlin.de.|Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany. emad.aziz@helmholtz-berlin.de.
authors.forename: Emad F
authors.initials: EF
authors.lastname: Aziz
keywords: X-ray spectroscopy; density functional calculations; frontier orbitals; liquids; ureas