Measurement of vibrational energy transfer of OH (A 2 Σ + ,v ′ =1→0) in low-pressure flames

Experimental study of signal trapping of OH laser induced fluorescence and chemiluminescence in flames

“…For the LIF measurements this fact reduces signal trapping because after excitation of ν = 1 VET is not fast enough to populate ν = 0 to an extent corresponding to thermal equilibrium. The vibrational and rotational redistribution has been well characterized in previous investigations [25,26], however, the final effect on signal trapping has, to the authors' knowledge, not been demonstrated before with spectral resolution. OH* chemiluminescence instead is mainly concentrated in the (0,0) band and thus more prone to re-absorption.…”

Energy transfer in the OH A2Σ+state: The role of polarization and of multi-quantum energy transfer

“…It has been shown, that the LASKIN program can reasonably well reproduce experimental spectra taken under a wide range of conditions of pressure, temperature and composition. 7,8,16,[25][26][27]33 Whereas the first version of LASKIN has been developed to model rotational energy transfer processes in the OH A 2 S 1 state, it has subsequently been extended to investigate effects of VET using different model assumptions, 26 VET to higher states 8 and to model spectra of other molecules such as CH A 2 D 16 as well. The executable program can be obtained free of charge by request.…”

“…For the OH radical in the excited A 2 S 1 state, vibrational energy transfer has been investigated for some time. 8,[24][25][26][30][31][32][33] Apart from the quite different magnitude of VET rate coefficients for several combustion-relevant colliders 32,34 and the dependence of VET on rotational quantum number, 30,33 one interesting aspect is the potential occurrence of multiquantum transfer which has already been discussed in early studies. 30,35 Also, it has been noted that some of the energy transferred in a VET collision appears as rotational energy in a lower vibrational quantum state.…”

Oh Concentration Measurements in a Jet Engine Exhaust

“…Rate coefficients for collisional quenching of the ν′ = 0 level of excited OH by N 2 , O 2 , CO 2 , and H 2 O were taken from Tamura et al (1998). Vibrational energy transfer rate coefficients for the relaxation of ν′ = 1 to ν′ = 0 were taken from Hartlieb et al (1997), who also provided an estimation of the rate coefficients for collisional quenching of the ν′ = 1 level to be 80% of the values for the ν′ = 0 level, and the Einstein emission rates for fluorescence were obtained from Copeland, Jeffries, and Crosley (1987). Given the narrow bandwidth interference filter used in the experiments, only fluorescence from ν′ = 0 was observed; therefore, the model was used to investigate the effect on fluorescence from this level caused by the differing conditions in the flame and the HES, assuming an initial population of OH either in ν′ = 0 for which the theoretical model should apply, or an initial population of OH in ν′ = 1 as in the experimental measurements.…”