''Fluorescence'' interference with Raman measurements in nonpremixed flames of methane

Journal Article · Fri May 01 04:00:00 EDT 1987 · Combust. Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(87)90050-2· OSTI ID:6558139

Masri, A R; Bilger, R W

What appears to be fluorescence has been measured in the blue (visibly soot free) regions of laminar and turbulent nonpremixed flames of methane at atmospheric pressure. The measurements are part of an experiment to measure the spontaneous Raman scattering of eight species in the flame. The flames studied range from ones with low mixing rates to flames close to extinction. The ''fluorescence'' is nonresonantly excited by a pulsed dye laser and has been routinely monitored at lambda = 516.5 nm which is a bandhead of diatomic carbon, C/sub 2/. It is Stokes ''fluorescence'' that interferes with the Raman signal detection. It is found that the ''fluorescence'' is broadband covering all the visible spectrum, and is observed only on the rich side of stoichiometry with noticeable intensities for fuel number densities in the range 0.1 to approx. = 1.5 x 10/sup 18/ cm/sup -3/. The ''fluorescence'' intensity is of the order of the Raman signals, increases with the fourth power of the laser flux, is unaffected by flame stretch, and decreases with dilution of the unburned methane. No ''fluorescence'' is detected at temperatures below approx. = 1000/sup 0/C.

• Research Organization: Dept. of Mechanical Engineering, The Univ. of Sydney
• OSTI ID: 6558139
• Journal Information: Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 68:2; ISSN CBFMA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
ATMOSPHERIC PRESSURE
CARBON
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
DILUTION
DYE LASERS
ELEMENTS
FLAME PROPAGATION
FLAMES
FLUID FLOW
FLUORESCENCE
HYDROCARBONS
KINETICS
LAMINAR FLOW
LASERS
LIQUID LASERS
LUMINESCENCE
METHANE
MIXING
MONITORING
NONMETALS
ORGANIC COMPOUNDS
PULSE TECHNIQUES
RAMAN EFFECT
REACTION KINETICS
SCATTERING
SIGNALS
TURBULENT FLOW
VERY HIGH TEMPERATURE
WAVELENGTHS