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Title: High-resolution, vacuum-ultraviolet absorption spectrum of boron trifluoride

In the course of investigations of thermal neutron detection based on mixtures of {sup 10}BF{sub 3} with other gases, knowledge was required of the photoabsorption cross sections of {sup 10}BF{sub 3} for wavelengths between 135 and 205 nm. Large discrepancies in the values reported in existing literature led to the absolute measurements reported in this communication. The measurements were made at the SURF III Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. The measured absorption cross sections vary from 10{sup −20} cm{sup 2} at 135 nm to less than 10{sup −21} cm{sup 2} in the region from 165 to 205 nm. Three previously unreported absorption features with resolvable structure were found in the regions 135–145 nm, 150–165 nm, and 190–205 nm. Quantum mechanical calculations, using the TD-B3LYP/aug-cc-pVDZ variant of time-dependent density functional theory implemented in Gaussian 09, suggest that the observed absorption features arise from symmetry-changing adiabatic transitions.
Authors:
; ; ; ;  [1] ; ; ;  [2] ;  [3] ;  [1] ;  [4] ;  [4]
  1. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
  2. Nuclear Engineering Program, University of Maryland, College Park, Maryland 20742 (United States)
  3. Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
22415375
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 19; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ABSORPTION SPECTRA; BORON FLUORIDES; CROSS SECTIONS; DENSITY FUNCTIONAL METHOD; DETECTION; MIXTURES; SYNCHROTRONS; THERMAL NEUTRONS; TIME DEPENDENCE; WAVELENGTHS