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In situ cell for x-ray absorption spectroscopy of low volatility compound vapors

DOI: 10.1063/5.0006721 DOI Help

Authors: Alexander Levish (University of Duisburg-Essen) , Markus Winterer (University of Duisburg-Essen)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Review Of Scientific Instruments , VOL 91

State: Published (Approved)
Published: June 2020
Diamond Proposal Number(s): 19229

Abstract: Technologically relevant gas phase processes rely on reactants in vapor form for the production of thin films and nanoparticles. An instrument is described which enables the investigation of such vapors by x-ray absorption spectroscopy. Corresponding in situ studies provide information about gas phase precursor chemistry and optimized synthesis processes. The setup consists of a sealed vapor container heated by a hot air bath. Inert gas filling and temperature monitoring are implemented. Fluid dynamic simulations reveal a homogeneous temperature distribution without hot or cold spots. Temperature stability better than 1 K for at least 190 min allows time-dependent measurements or improved signal to noise ratios by averaging of datasets. Iron acetylacetonate is studied as a model system. X-ray absorption spectra measured by fluorescence are of high quality, allowing a detailed analysis of X-ray Absorption Near Edge Structure (XANES) and extended x-ray absorption fine structure. A molecular structure transformation is observed in XANES spectra of iron acetylacetonate vapor above 480 K probably due to the loss of one ligand. The setup allows the investigation of low volatility compounds with vapor pressures above 2 kPa at temperatures up to 520 K.

Journal Keywords: Fluorescence spectroscopy; Semiconductor detectors; Synchrotron X ray spectroscopy; Ionization chambers; Gas phase; Thin films; Chemical vapor deposition; Nanoparticles; Extended X-ray absorption fine structure; X-ray absorption spectroscopy

Subject Areas: Chemistry, Technique Development

Instruments: I20-Scanning-X-ray spectroscopy (XAS/XES)

Other Facilities: DESY