# PERTURBED AND DEPERTURBED FLUORESCENCE LIFETIMES OF SINGLE VIBRONIC LEVELS OF THE $CO A^{1}\Pi$ STATE

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 Title: PERTURBED AND DEPERTURBED FLUORESCENCE LIFETIMES OF SINGLE VIBRONIC LEVELS OF THE $CO A^{1}\Pi$ STATE Creators: Field, R. W.; D'azy, O. Benoist; Lavollee, M.; Lopez-Delgado, R.; Tramer, A. Issue Date: 1977 Publisher: Ohio State University Abstract: We have utilized the nanosecond pulse time structure of ACO synchotron radiation to record fluorescence decay curves from isolated CO molecules in the $A^{1}\Pi$ electronic state. With broad band excitation ($\sim$10 {\AA}) the fluorescence decay from single vibronic levels was found to be generally nonexponential. Under a narrow band excitation $(0.3 {\AA})$ pumping a few rovibronic levels, the form of decay depends on $\lambda_{exc}$ within a vibronic band contour. These effects are due to the perturbations of the $A^{1}\Pi$ levels by neighboring levels belonging to the $e^{3}\Sigma^{-}, {a{^{\prime}}}^{3}\Sigma^{+}$ and $d^{3}\Delta$ triplet states. By assuming the wave functions of individual rovibronic states as: $$\| n> = a\|s>+ \Sigma\_{i} b_{i}\|t_{i}>$$ (where a and $b_{i}$ are determined by analysis of perturbations) and their radiatives rates as: $\gamma_{n} = a^{2}\gamma _{S}$ (where $Y_{S}$ is the radiative rate of the pure” singlet vibronic level) we obtained computer simulations of decay curves. From the best fits of calculated and experimental curves, the values of $Y_{S}$ for vibronic levels $v = 0$ to 7 were determined and their dependence on v and on the r-centroid will be discussed."" Description: Author Institution: Massachusetts Institute of Technology; Laboratoire de Photophysique CNRS and LURE URI: http://hdl.handle.net/1811/10063 Other Identifiers: 1977-Pi-05