21 November 1997 Density measurements in high-pressure nitrogen using spontaneous Raman scattering of 248-nm laser light
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Abstract
As part of a program to develop methods for imaging combustion processes in engines using tunable excimer lasers, we have studied the pressure dependence of vibrational Raman scattering from nitrogen at pressures up to 60 atm. Tunable, powerful UV-lasers have an advantage over visible lasers because many types of physical light scattering mechanisms can be used with only minor changes of equipment. The intensity of Raman scattering at UV wavelengths is very strong because it varies as the fourth power of the laser frequency. We can simultaneously acquire a 1D image of temperature as well as of the density of all the major constituents. Alternatively we can use line-of- sight Raman in a back-scatter mode in which only tow very small windows are needed for optical access. In order to do all of this, the differential Raman cross section must be shown to be independent of pressure. Since nitrogen is often taken as the reference material, with the Raman cross sections for other gases measured relative to it, we demonstrate the pressure independence for nitrogen.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Youngwei Gu, Yanhua Zhou, Erhard W. Rothe, Yi Su, Gene P. Reck, "Density measurements in high-pressure nitrogen using spontaneous Raman scattering of 248-nm laser light", Proc. SPIE 3172, Optical Technology in Fluid, Thermal, and Combustion Flow III, (21 November 1997); doi: 10.1117/12.293416; https://doi.org/10.1117/12.293416
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KEYWORDS
Nitrogen

Raman spectroscopy

Raman scattering

Laser scattering

Light scattering

Combustion

Image processing

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