Theoretical investigation of the Cs∗Hen⩾3 exciplexes

The X2Σ1/2, A2Π1/2, B2Σ1/2, and A2Π3/2 states of Cs∗Hen exciplexes, with n={3,…,9}, are studied using first principle density functional theory (DFT) formalism combined with the zeroth order regular approximation (ZORA). The zero points energies (ZPEs) E0 for Cs∗Hen are calculated at a first step, in order to estimate the stability of the studied exciplexes. Relativistic calculations are carried out including spin-orbit effect (SO), and potential energy surfaces of Cs∗He6 are shown. The electronic distribution shapes of the studied molecules are also discussed, and their emission lines are evaluated and compared to a new discovered experimental emission spectra, which has been recently assigned, using a semi-empirical model, to Cs(AΠ1/2)He7. Our first principle calculation suggests that the discovered emission line is most probably due to a decay of Cs(AΠ1/2)He6.