MEASUREMENTS OF HIGHLY-FORBIDDEN OPTICAL TRANSITIONS BY CW DYE LASER SPECTROSCOPY

Abstract

Intracavity cw dye laser quenching has been used to observe highly-forbidden transitions near 6300 {\AA}: (1) the 2,0 band of the atmospheric system $[b^{1}\Sigma^{+}_{g} \leftarrow X^{3}\Sigma^{-}_{g}]$ of molecular oxygen and (2) the 6,0 overtone bands of $H^{35}Cl$. Briefly, 100-700 Torr of sample gas within an 80 cm pathlength cell was mounted within the cavity of a free-running Rhodamine B cw dye laser pumped by 2-4 W of 5145 {\AA} argon ion laser radiation; dye laser output was detected with an optical multichannel analyzer mounted on a one-meter grating monochromator, sensitivity tests indicate that band systems with oscillator strengths less than. $10^{-12}$ can be readily detected, thereby suggesting routine use for high-resolution optical spectroscopy of forbidden transitions.