Cavity ringdown laser absorption spectroscopy of the jet-cooled aluminum dimer

The 2 3Π−X 3Π electronic band system of the aluminum dimer has been measured with the CRLAS technique. While several vibronic bands were examined under high resolution, no rotational features could be discerned. Band contours imply a rapid (τ < 10 ps) predissociation in the upper state, explaining why this band system was not observed in previous R2PI and LIF studies. The upper electronic state was determined to have a vibrational frequency of 210 ± 4 cm−1.