Knowledge Bank

A new, folder-variant of optical-optical double resonance has been developed for the state-specific characterization of polyatomic species that contain chemically-significant quantities of vibrational $excitation1$. Based upon a phase-conjugate implementation of degenerate four-wave mixing (DFWM) spectroscopy, this technique offers substantial advantages, both in terms of sensitivity and resolution, over more conventional methodologies. Despite the third-order nonlinearity inherent to the DFWM process, the tremendous resonant enhancement that accompanies this interaction enables the facile detection of doubleresonance signals even under low pressure (viz.,<10$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$Torr), bulk gas conditions. Application of this scheme will be discussed with paricular emphasis on the the rovibrational structure exhibited by $CS2$ molecules that have up to 20,000$cm-1$ of energy selectively deposited into their internal degrees of freedom [i.e., roughly 60% of $D\circ circ$(SC--S)]. the spectral simplification afforded by the double resonance natur of this technique has also permitted a complete and systematic reanalysis of the perturbed origin band for the $CS2V1B2-X1\Sigma g+$ transition.