Rotational pathways in electronic energy transfer

We analyze rotational distributions from collision-induced atom-diatom elec tronic energy transfer (EET) experiments in terms of the capacity of the di atomic to dispose of the angular momentum (AM) generated in state-to-state change. Two pairs of systems are chosen as representative of processes broa dly categorized as "efficient" or "inefficient" in this regard, namely, Na- 2-Na, Li-2-Li in the former category and N-2(+)-He, CN-Ar in the latter. No te that EET involving electron spin change is not considered here. Using ve locity-AM diagrams and quantitative calculations we show the factors that g overn the probability of state-to-state transfer in EET are the same as tho se controlling the outcome of rotational and rovibrational transfer within an electronic state. This suggests that requirements of orbital and rotatio nal AM are of critical importance in providing pathways that allow EET to p roceed. (C) 2001 American Institute of Physics.