Quantitative laser-induced fluorescence of CH in atmospheric pressure flames |
| |
Authors: | J Luque RJH Klein-Douwel JB Jeffries GP Smith DR Crosley |
| |
Institution: | (1) Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025 USA, US |
| |
Abstract: | Absolute number densities of the CH radical were determined in a partially premixed methane/air flame (equivalence ratio was
1.36) at atmospheric pressure by exciting a predissociating level via the CH B–X(1,0) transition using a quasi-linear laser-induced
fluorescence scheme. The peak number density was (1.0±0.4)×1013 cm-3 or 2.4±1 ppm at 1900 K, with a flame-front width of 250 μm (FWHM). Rotational energy transfer must be considered for correct
laser-induced fluorescence signal interpretation. Competition between optical pumping and rotational relaxation in both excited
and ground states produces a signal that varies almost linearly with laser pulse energy even for large pumping rates. For
these conditions, the population of the initial ground-state rotational level is depleted by optical pumping, and rotational
energy transfer collisions rapidly repopulate the level during the laser pulse. Deviations from linear behavior are less than
20%. The effects of spatial resolution and polarization of the fluorescence on the absolute measurements are also discussed.
Received: 27 March 2002 / Revised version: 22 August 2002 / Published online: 15 November 2002
RID="*"
ID="*"Present address: Lam Research Corporation, Fremont, CA 94538, USA
RID="**"
ID="**"Present address: Mechanical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
RID="***"
ID="***"Present address: Mechanical Engineering Dept., Stanford University, Stanford CA 94305, USA
RID="****"
ID="****"Corresponding author. Fax: +1-650/859-6196, E-mail: smith@mplvax.sri.com |
| |
Keywords: | PACS: 82 80 Dx 42 62-b 34 50 Ez |
本文献已被 SpringerLink 等数据库收录! |
|