DIODE LASER STUDY OF THE $v_{4}$ FUNDAMENTAL OF $C_{3}O_{2}$
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Date
1975
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Ohio State University
Abstract
We have used current-tunable, thin-film PbTe diode lasers to obtain Doppler-limited resolution of the $v_{4}$ band of $C_{3}O_{2}$ in the region 1565-1600 $cm^{-1}$. Roughly 60\% of the interval was covered using different modes of 2 lasers, each mode giving a tuning range of 1-3 cm$^{-1}$, Calibration was obtained with H$_{2}$O and NH$_{3}$, while the frequency scale was given by the fringes of a 4-cm Ge etalon, recorded simultaneously using a double beam technique. Near 1600 cm$^{-1}$ a set of strong regularly spaced lines stands out, which is the R branch of the ground state transition. This band as wel as the ``hot” bands due to the bending vibration $v_7$ indicate a linear structure for the molecule. Preliminary values in cm$^{-1}$ for the ground state are $v_0=$ 1587.392, B^{\prime\prime} - 0.07557, and B$^{\prime}$ - B$^{\prime\prime} = 6.414 \times 10^{-4}$. This B^{\prime\prime} value differs from that reported by Lafferty et al.,$^{1}$ but agrees with that by Mantz et al.$^{2}$ The next 2 strongest series were interpretable as a $\Pi$ band with $\nu_0$ = 1580.910, B$^{\prime\prime}_{c}$ = 0.07606, B$^{\prime\prime}_{d}$ - 0.07646, B$^{\prime\prime}_{c}$ - B$^{\prime\prime}_{c}$ = 4,178 X 10$^{-4}$, B$^{\prime}_{d}$ - B$^{\prime\prime}_{d}$ = 5.259 $\times$ 10$^{-4}$. These B$^{\prime\prime}$ values agree with Assignment 2 by Lafferty et al.$^{1}$ The assignment of the ground state transition and the shift of the “hot” bands toward lower frequency were substantiated by temperature-difference FTS spectra.
Description
$^{1}$ W. J. Lafferty, A. G. Maki, and E. K. Plyler, J. Chem. Phys. 40, 224 (1964).$^{2}$ A. W. Mantz, P. Connes, G. Guelachvili, and C. Amiot, J. Mol. Spectrosc. 54, 43 (1975).""
Author Institution: Scientific Research Staff Ford Motor Company; Department of Physics, The University of Michigan
Author Institution: Scientific Research Staff Ford Motor Company; Department of Physics, The University of Michigan