EVIDENCE FOR THE PREPARATION OF A NON-STATIONARY STATE OF $NO_{2}$ FROM OPTICAL RADIO FREQUENCY DOUBLE RESONANCE SPECTRA

$^{1}$ H. G, Weber, P. J. Brucat, and R. N. Zare, Chem. Phys. Lett. (accepted for publication). $^{2}$ H. G. Weber, P. J. Brucat, and R. N. Zare. Chem. Phys. Lett. 60, 179 (1979). $^{3}$ H. Figger, D. L. Monts, and R. N. Zare, J. Mol. Spec. 68, 388 (1977). We gratefully acknowledge support for this research from the National Science Foundation.Author Institution:In addition to the narrow resonances from the hyperfine components of the particular rotational line of the $NO_{2}\ ^{2}B_{2}$ state excited, a broad resonance appears in the ORDER $spectrum.^{1}$ This resonance has a pressure independent lifetime of $0.4 \pm 0.1$ us which is attributed to the ``lifetime’’ of a non-stationary state prepared by the excitation source. This lifetime corresponds to the lifetime $\tau_{o}$ introduced in a simple model of the dephasing and radiative lifetimes of $NO_{2}.^{2}$ According to this model the dephasing lifetime, $\tau_{c}$, depends on $\tau_{o}$ and the rotational quantum number N as follows: \begin{equation} \tau_{c} = \tau_{o} (2N + 1) \end{equation} Dephasing times measured in the Hanle effect are well predicted by this $model.^{3}