Knowledge Bank

Fifty 3$3\Sigma g+$ {\em v}$=2-9\leftarrow$ {\em X}$1\Sigma g+$ two-photon transitions of Cs$2$ have been observed in the infrared wavelength. Vibrational resolved fluorescence into both bound levels and the continuum of the {\em a}$3\Sigma u+$ state has been recorded with monochromator. Calculated 3$3\Sigma g+\to$ {\em a}$3\Sigma u+$ fluorescence spectra are compared with observed spectra. With two infrared diode lasers,totally 43 ro-vibrational levels of the Cs$2$ 3$3\Pi g$ state have been observed by perturbation facilitated infrared-infrared double resonance spectroscopy. Rotationally resolved fluorescence to the {\em a}$3\Sigma u+$ state was also recorded.