# TEMPERATURES FROM ROTATIONAL-VIBRATIONAL RAMAN Q-BRANCHES

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 Title: TEMPERATURES FROM ROTATIONAL-VIBRATIONAL RAMAN Q-BRANCHES Creators: Hill, R. A.; Mulac, A. J.; Aeschliman, D. P.; Flower, W. L. Issue Date: 1978 Publisher: Ohio State University Abstract: A scheme, based on the differential of the intensity, $dI = d\tau \partial I/\partial \tau + d\rho \partial I/\partial \rho$, has been developed for obtaining temperature $T = 1/\tau$ and density $\rho$ from rotational-vibrational Raman Q-branches, The differences between calculated intensities, and intensities observed in a passband f(v) are analyzed by a least squares technique with the expression: $I_{obs} - I_{calc} = (\tau^{*} - \tau) \sum_{\nu} \frac{\partial I}{\partial \tau} f(\nu) + (\rho^{*} - \rho) \sum_{\nu} \frac{\partial I}{\partial \rho} f(\nu)$ which represents an extrapolation from starting values T and p to revised values $T^{*}$ and $\rho^{*}$ with derivatives evaluated with the starting values. The revised values are used to calculate a new set of intensities and derivatives; the process is iterated until a stable set of $T^{*}$ and $\rho^{*}$ are obtained. To determine the spectral locations that caver the maximum variation in $\partial I/\partial \tau$, a set of intensities and derivatives were calculated as a function of frequency $\nu$ and temperature. The results for the Stokes (anti-Stokes) bands indicate for temperatures less than $2100^{\circ}\;K$ $(2700^{\circ}\;K$) the maximum extent of $\partial I/\partial \tau$ can be spanned by recording intensities only in the first two vibrational bands, v(1-0) and $\nu(2-1)$, and due to the multivalued nature of $\partial I/\partial \tau$, equally spaced values for $\partial I/\partial \tau$ can be obtained only by programming the spectrometer to select an appropriate set of non-uniformly spaced passbands. Description: This work was supported by the United States Department of Energy. Author Institution: Sandia Laboratories; Sandia Laboratories URI: http://hdl.handle.net/1811/10511 Other Identifiers: 1978-RE-11