Reactive scattering of rydberg atoms: H* + D2 --> HD + D*.

The scattering of highly excited hydrogen Rydberg atoms, H* (n = 36), with deuterium molecules in their rovibrational ground state, D2(v = 0, j = 0), has been investigated at a relative collision energy of 0.53 eV. Time-of-flight distributions of elastically/inelastically scattered H* Rydberg atoms and reactively scattered D* Rydberg atoms have been measured at different laboratory angles. The extracted rovibrationally resolved state distributions of the HD product molecules from reactive collisions resemble closely those reported for the corresponding ion-molecule reaction, H+ + D2 --> HD + D+. This similarity is rationalised using the free electron model which predicts that the Rydberg electron acts as a spectator while the ionic reaction takes place.