Optical Refractivity of High-Temperature Gases. III. The Hydroxyl Radical

Abstract

The optical refractive index has been measured interferometrically behind Mach 6 to 9 shock waves advancing into nearly equimolal hydrogen and oxygen at pressures of 0.01, 0.015, and 0.02 atm. Pressure measurements in these experiments together with other data on similar systems show the shocked gas to be in an equilibrium state. The refractivity to be expected from all species present, except the hydroxyl radical, is computed, and the difference between this and the observed refractivity is attributed to hydroxyl radical present at the equilibrium density. The resultant specific refractivity in the blue is K = 0.35 ± 0.04 cm3/g, corresponding to a polarizability of ᾱ = 1.5 ± 0.2A3 and a refractivity of μ − 1 = (2.5 ± 0.3) × 10−4.

Measurement of temperature and concentration in oxy-fuel flames by Raman/Rayleigh spectroscopy

“…We use a similar approach to measure σ Ray,OH at 248 nm as [26] for the visible: interferometric measurements of the refractive index n of a progressing reaction in H 2 /O 2 mixtures are compared to refractive indices calculated from equilibrium concentrations. The free parameter is the contribution by OH (n OH ).…”

“…The free parameter is the contribution by OH (n OH ). From fitting a value for n OH , σ Ray,OH was derived [24,26].…”

“…For this purpose a laminar H 2 /O 2 diffusion flame is used and Rayleigh and Raman signals are measured for a broad range of equivalence ratios. The assignment of a mixture fraction to a specific measurement is done not temporally (as in [26]) or spatially, but by signal intensities of the H 2 O Raman signal as the least disturbed signal for 248 nm excitationcompare figure 6.…”

Methane oxidation near a cold wall

“…The Gladrrtone-Dale constants K i for the different species were taken from Borchers et al (1962), Alpher &White (1959) andWhite (1961), except for the components CH,, H,CO, HCO and H,O for which the same value as those for CH,, CO and 0,…”