Occupied and unoccupied electronic structures of an L-cysteine film studied by core-absorption and resonant photoelectron spectroscopies

Abstract

Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4, m ≥ 3) orbitals. Resonant photoelectron spectra at S-L23 and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively.

Effects of Embedded TiO2−x Nanoparticles on Triboelectric Nanogenerator Performance

“…Figure 4 a shows the hybridized molecular orbital structures in the conduction band of the TiO 2−x NPs-embedded PDMS as a function of the weight ratio of TiO 2−x NPs measured by XAS. The normalized intensities of the oxygen K-edge spectra of pristine PDMS and TiO 2−x NPs-embedded PDMS layers directly reflect the unoccupied hybridized states by the transition of electrons from the occupied O 1 s state [ 17 ]. Figure 4 a co-plots the normalized O-K edge XAS spectrum of TiO 2−x NPs (gray lines) for easy comparison with the changes in the TiO 2−x NPs-embedded PDMS layer spectra.…”

Effects of l-ascorbic acid (C6H8O6: Vit-C) on collagen amino acids: DFT study

“…The most important parameter to be studied is the gap energy between the HOMO and LUMO orbitals, which is called gap energy (E g ). the other parameters are calculated according to the following equations [14][15][16]:…”