Scheme for state-selective formation of highly rotationally excited diatomic molecules

A scheme is proposed for making highly rotationally excited diatomic molecules (“super rotors”) in their ground vibrational and electronic state, e.g., 6Li2X 1Σg+ (v=0,J⩾115) where the rotational energy exceeds the bond strength (E(0,J)−E(0,0)⩾D00). Such levels, while strictly speaking quasibound, have very long tunneling lifetimes (>1011 s for J⩽130), and should have very interesting and unique collisional properties, especially at low temperature. The rotation of the molecules is “spun up” by sequential irradiation by R branch photons in the A 1Σu+–X 1Σg+ bands starting with cold molecules at low J. Spontaneous emission to other vibrational levels is overcome by using a pump laser and its multiple Raman sidebands as in previous work on “spinning down” diatomics.