skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Soft X-ray spectroscopy of nanoparticles by velocity map imaging

Authors:
ORCiD logo [1];  [1];  [2]; ORCiD logo [1]
  1. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  2. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA, Department of Chemistry, University of California, Berkeley, California 94720, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1361864
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 147; Journal Issue: 1; Related Information: CHORUS Timestamp: 2018-02-15 00:49:32; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Kostko, O., Xu, B., Jacobs, M. I., and Ahmed, M.. Soft X-ray spectroscopy of nanoparticles by velocity map imaging. United States: N. p., 2017. Web. doi:10.1063/1.4982822.
Kostko, O., Xu, B., Jacobs, M. I., & Ahmed, M.. Soft X-ray spectroscopy of nanoparticles by velocity map imaging. United States. doi:10.1063/1.4982822.
Kostko, O., Xu, B., Jacobs, M. I., and Ahmed, M.. Fri . "Soft X-ray spectroscopy of nanoparticles by velocity map imaging". United States. doi:10.1063/1.4982822.
@article{osti_1361864,
title = {Soft X-ray spectroscopy of nanoparticles by velocity map imaging},
author = {Kostko, O. and Xu, B. and Jacobs, M. I. and Ahmed, M.},
abstractNote = {},
doi = {10.1063/1.4982822},
journal = {Journal of Chemical Physics},
number = 1,
volume = 147,
place = {United States},
year = {Fri Jul 07 00:00:00 EDT 2017},
month = {Fri Jul 07 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4982822

Save / Share:
  • We have employed a unique spectroscopic approach, a resonant inelastic soft x-ray scattering (RIXS) map, to identify and separate electron-hole correlation effects in core-level spectroscopy. With this approach, we are able to derive a comprehensive picture of the electronic structure, separating ground state properties (such as the HOMO-LUMO separation) from excited state properties (such as the C 1s core-exciton binding energy of C{sub 60}). In particular, our approach allows us to determine the difference between core- and valence exciton binding energies in C{sub 60}[0.5 ({+-}0.2) eV]. Furthermore, the RIXS map gives detailed insight into the symmetries of the intermediate andmore » final states of the RIXS process.« less
  • The crystal structure of magnetite nanoparticles may be transformed to maghemite by complete oxidation, but under many relevant conditions the oxidation is partial, creating a mixed-valence material with structural and electronic properties that are poorly characterized. We used X-ray diffraction, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, and soft X-ray absorption and emission spectroscopy to characterize the products of oxidizing uncoated and oleic acid-coated magnetite nanoparticles in air. The oxidization of uncoated magnetite nanoparticles creates a material that is structurally and electronically indistinguishable from maghemite. By contrast, while oxidized oleic acid-coated nanoparticles are also structurally indistinguishable from maghemite,more » Fe L-edge spectroscopy revealed the presence of interior reduced iron sites even after a 2-year period. We used X-ray emission spectroscopy at the O K-edge to study the valence bands (VB) of the iron oxide nanoparticles, using resonant excitation to remove the contributions from oxygen atoms in the ligands and from low-energy excitations that obscured the VB edge. The bonding in all nanoparticles was typical of maghemite, with no detectable VB states introduced by the long-lived, reduced-iron sites in the oleic acid-coated sample. However, O K-edge absorption spectroscopy observed a 0.2 eV shift in the position of the lowest unoccupied states in the coated sample, indicating an increase in the semiconductor band gap relative to bulk stoichiometric maghemite that was also observed by optical absorption spectroscopy. The results show that the ferrous iron sites within ferric iron oxide nanoparticles coated by an organic ligand can persist under ambient conditions with no evidence of a distinct interior phase and can exert an effect on the global electronic and optical properties of the material. This phenomenon resembles the band gap enlargement caused by electron accumulation in the conduction band of TiO2.« less
  • We report (nanosecond) resonance-enhanced multiphoton ionization (REMPI), (nanosecond) zero-kinetic-energy (ZEKE) and (picosecond) time-resolved slow-electron velocity map imaging (tr-SEVI) spectra of fully hydrogenated toluene (Tol-h{sub 8}) and the deuterated-methyl group isotopologue (α{sub 3}-Tol-d{sub 3}). Vibrational assignments are made making use of the activity observed in the ZEKE and tr-SEVI spectra, together with the results from quantum chemical and previous experimental results. Here, we examine the 700–1500 cm{sup −1} region of the REMPI spectrum, extending our previous work on the region ≤700 cm{sup −1}. We provide assignments for the majority of the S{sub 1} and cation bands observed, and in particular wemore » gain insight regarding a number of regions where vibrations are coupled via Fermi resonance. We also gain insight into intramolecular vibrational redistribution in this molecule.« less
  • No abstract prepared.