Knowledge Bank

The fluorescence of iodine vapor corresponding to the transition $B3\Pi ou+-X1\Sigma ou+$ was studied at room temperature $(20\circ C)$ using a pulsed argon ion laser as the excitation source. An assignment was made for the levels reached by the argon excitation. It was found that the following lines in the iodine absorption spectrum overlapped with the $5145.36\backslash AA$ argon line: $(51-1),P(53);(50-1),P(39);(49-1),P(18):(43-0),P(12),R(14);(45-0),P(64)$. The occurrence of the $v\prime =43$ and $v\prime =49$ band series in the fluorescence agrees with the assignment of Ezekiel and $Weiss1$ in their work on laser induced fluorescence in an iodine molecular beam. Quenching cross sections were measured for a variety of inert gases, including He, Ne, Ar, Xe, and Kr; and from the study of the fluorescence side bands, vibrational-rotational energy transfer cross sections were determined. Self quenching cross sections for iodine vapor were also measured, taking into account the self-absorption of radiation. The depolarization of individual rotational lines in the resolved spectrum at low pressure in the presence of foreign gases will be discussed with reference to the molecular reorientation on collision, along the lines formulated by $Gordon.2$