Time-Resolved Vibrational Spectroscopy to Measure Lifetime of the E$^3\Pi_g(v=3)$ state of Molecular Iodine

The lifetime of the $E^3\Pi_g(v=3)$ state of molecular iodine was measured in the gas phase at room temperature. The $E^3\Pi_g$ state was selectively populated by two sequential nanosecond pulse laser excitation. Resolved molecular fluorescence for the $B^3\Pi_u^+\leftarrow E^3\Pi_g$ was analyzed and the lifetime of the $E(v=3)$ state, measured using a time-correlated single photon counting technique, is to be $\tau=21 (2)$ ns.