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Rotational coherent anti-Stokes Raman spectroscopy (CARS) in nitrogen at high pressures (0.1-44 MPa) : Experimental and modelling results

Bood, Joakim LU ; Bengtsson, Per Erik LU and Dreier, Thomas (2000) In Journal of Raman Spectroscopy 31(8-9). p.703-710
Abstract

Pure rotational coherent anti-Stokes Raman scattering (CARS) has for the first time been investigated for pressures up to 44 MPa in nitrogen gas at room temperature. An atomic filter consisting of a heated cell with sodium vapour was successfully applied for suppression of stray light originating from the narrowband CARS pump laser beam. With increasing pressure the rotational CARS spectrum is smoothed gradually, and above around 10 MPa spectral lines are no longer resolvable. Experimental data were compared using Raman linewidths calculated with three different models: the energy corrected sudden scaling law (ECS), the modified exponential gap model (MEG), and a semi-classical ab initio model. All three models resulted in bad spectral... (More)

Pure rotational coherent anti-Stokes Raman scattering (CARS) has for the first time been investigated for pressures up to 44 MPa in nitrogen gas at room temperature. An atomic filter consisting of a heated cell with sodium vapour was successfully applied for suppression of stray light originating from the narrowband CARS pump laser beam. With increasing pressure the rotational CARS spectrum is smoothed gradually, and above around 10 MPa spectral lines are no longer resolvable. Experimental data were compared using Raman linewidths calculated with three different models: the energy corrected sudden scaling law (ECS), the modified exponential gap model (MEG), and a semi-classical ab initio model. All three models resulted in bad spectral fits when a linear scaling with pressure was employed. By using additional scale factors for the Raman linewidths the quality of the spectral fits and also the temperature accuracy were significantly improved. The resulting scale factors indicate a non-linear pressure dependence of the linewidths, and visualize a narrowing of the spectral envelope at the highest pressure, i.e. 44 MPa. The results indicate shortcomings in the present isolated line models and also emphasize the need for new experimental data on pure rotational Raman linewidths at high density. Copyright (C) 2000 John Wiley and Sons, Ltd.

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author
organization
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type
Contribution to journal
publication status
published
in
Journal of Raman Spectroscopy
volume
31
issue
8-9
pages
8 pages
publisher
John Wiley & Sons
external identifiers
  • Scopus:0033647456
ISSN
0377-0486
language
English
LU publication?
yes
id
75433b58-9e5d-4539-8a44-4e3fb22a2d24
date added to LUP
2016-06-29 17:34:23
date last changed
2016-07-15 11:29:34
@misc{75433b58-9e5d-4539-8a44-4e3fb22a2d24,
  abstract     = {<p>Pure rotational coherent anti-Stokes Raman scattering (CARS) has for the first time been investigated for pressures up to 44 MPa in nitrogen gas at room temperature. An atomic filter consisting of a heated cell with sodium vapour was successfully applied for suppression of stray light originating from the narrowband CARS pump laser beam. With increasing pressure the rotational CARS spectrum is smoothed gradually, and above around 10 MPa spectral lines are no longer resolvable. Experimental data were compared using Raman linewidths calculated with three different models: the energy corrected sudden scaling law (ECS), the modified exponential gap model (MEG), and a semi-classical ab initio model. All three models resulted in bad spectral fits when a linear scaling with pressure was employed. By using additional scale factors for the Raman linewidths the quality of the spectral fits and also the temperature accuracy were significantly improved. The resulting scale factors indicate a non-linear pressure dependence of the linewidths, and visualize a narrowing of the spectral envelope at the highest pressure, i.e. 44 MPa. The results indicate shortcomings in the present isolated line models and also emphasize the need for new experimental data on pure rotational Raman linewidths at high density. Copyright (C) 2000 John Wiley and Sons, Ltd.</p>},
  author       = {Bood, Joakim and Bengtsson, Per Erik and Dreier, Thomas},
  issn         = {0377-0486},
  language     = {eng},
  number       = {8-9},
  pages        = {703--710},
  publisher    = {ARRAY(0x93879e0)},
  series       = {Journal of Raman Spectroscopy},
  title        = {Rotational coherent anti-Stokes Raman spectroscopy (CARS) in nitrogen at high pressures (0.1-44 MPa) : Experimental and modelling results},
  volume       = {31},
  year         = {2000},
}