Electronic and Structural Properties of 'Smart Windows' and Liquids Using in-situ X-ray-Absorption Spectroscopy

Authors

Ponnusamy Nachimuthu, University of Nevada, Las VegasFollow
Shuji Matsuo, Fukuoka UniversityFollow
B. Farangis, Lawrence Berkeley National Laboratory
Dennis W. Lindle, University of Nevada, Las VegasFollow
H. Wakita, Fukuoka UniversityFollow
Rupert C. Perera, Lawrence Berkeley National LaboratoryFollow

Document Type

Article

Publication Date

1-2004

Publication Title

Journal of Alloys & Compounds

Volume

362

Issue

1-2

First page number:

124

Last page number:

132

Abstract

A new experimental set-up to measure in-situ X-ray absorption spectra under ambient conditions in the 400–2000-eV photon-energy region using both transmission and total-fluorescence-yield detection techniques has been developed, and its utility has been demonstrated by studying optically switchable and amorphous metal thin films (Mg–TM, where TM=Ti, Mn, Co and Ni) in the solid state, as well as Al³⁺ and Br⁻ions in aqueous solution. The structural and electronic properties of the freshly co-sputtered Mg–TM thin films in metallic and hydride states were investigated by X-ray diffraction and Mg K- and TM L-edge X-ray absorption spectra. The optical switching of Mg–TM thin films from a mirror-like metallic state to an optically transparent state by exposure to 4% H₂ in He is demonstrated by optical transmission and reflectivity in the 350–2500-nm region. The corresponding edge shifts in the Mg K- and TM L-edge X-ray absorption spectra indicate the presence of hydrogen as near neighbors, and its influence on the chemical states of metal thin films is demonstrated using Mg–Ni thin films as a representative example. Aluminum K-edge X-ray absorption spectra in the near-edge region were investigated to study the coordination of Al in crystalline and 0.1 M aqueous solutions of NaAlO₂, Al(NO₃)₃ and Al₂(SO₄)₃. Aluminum in NaAlO₂ occupies both tetrahedral and octahedral sites unlike Al in Al(NO₃)₃ and Al₂(SO₄)₃, where it retains its six-fold coordination irrespective of hydration. Bromine L-edge X-ray absorption spectra for crystalline and 0.1 M aqueous solutions of NaBr, KBr and KBrO₃ were carried out to study the ligand-field splittings of core excitations which depend on inter-atomic distances, dissociation in aqueous solution, and the resulting hydration.

Keywords

Absorption spectra; Aluminum; Bromine; Electronic states; Energy storage materials; Extended X-ray absorption fine structure (EXAFS); Near-edge X-ray absorption fine structure (NEXAFS); Synchrotron radiation; Thin films; X-ray Absorption Near Edge Structure

Disciplines

Analytical Chemistry | Atomic, Molecular and Optical Physics | Biological and Chemical Physics | Elementary Particles and Fields and String Theory | Physical Chemistry

Language

English

Permissions

Use Find in Your Library, contact the author, or use interlibrary loan to garner a copy of the article. Publisher copyright policy allows author to archive post-print (author’s final manuscript). When post-print is available or publisher policy changes, the article will be deposited

Repository Citation

Nachimuthu, P., Matsuo, S., Farangis, B., Lindle, D. W., Wakita, H., Perera, R. C. (2004). Electronic and Structural Properties of 'Smart Windows' and Liquids Using in-situ X-ray-Absorption Spectroscopy. Journal of Alloys & Compounds, 362(1-2), 124-132.