Isotope effects on the formation of the lowest rovibrational level of NaH molecule via pump–dump photoassociation

Abstract

The isotope effects, substituting H for D in the photoassociation (PA) of the NaH system, on the molecular formation of the lowest rovibrational level, $$|\upsilon =0,\,j=0\rangle$$ , in the electronically ground state $$(\hbox {X}^1\varSigma ^+)$$ via a pump–dump PA process are investigated using the time-dependent wavepacket method. Three cases are taken into account. In the case (1), the rovibrational level $$|\upsilon =10,\,j=1\rangle$$ of the $$\hbox {A}^1\varSigma ^+$$ state is taken as the intermediate state for the NaH system. In the case (2), the intermediate state is the same as that of the case (1) except for the NaD system. In the case (3), we set the intermediate state as $$|\upsilon =16,\,j=1\rangle$$ of the $$\hbox {A}^1\varSigma ^+$$ state for the NaD system. The PA probabilities of the three cases are $$64\,\%$$ [case (1)], $$5.5\,\%$$ [case (2)], and $$61\,\%$$ [case (3)]. It is shown that the PA results of these cases are in accordance with the continuum-bound Franck–Condon factors of the pump process. In addition, the effects of the time-dependent variation of the angular distribution of the prepared excited-state wavepacket on the PA probability are also discussed and compared for the two systems.