Experimental and theoretical studies of the ion-pair and valence states of the NeICl Van der Waals complexes

Experimental and theoretical studies of the $T$-shaped NeICl van der Waals (vdW) complexes in the ion-pair (IP) $E0^+$ $D'2$, $\beta1$ and valence $A1$ states as well as the NelCl ($A1$, $v_A$, $n_A\leftarrow X0^+$, $v_X=0$, $n_X$ и $\beta1$, $v_\beta$, $n_\beta/E_0^+$, $v_E$, $n_A\leftarrow A1$, $v_A$, $n_A$, $n_i$) optical transitions have been carried out (are vdW modes). We have measured (IP, $v_{\mathrm{IP}}=0$, $n_{\mathrm{IP}}\rightarrow$ valence states) luminescence spectra and their excitation spectra. Binding energies of the states have been determined. The NelCl (IP, $v_{\mathrm{IP}}=1$, $n_{\mathrm{IP}}$) $\rightarrow$ $\mathrm{Ne}+\mathrm{lCl}(E,D',\beta)$ decay has been also studied. The intermolecular diatomic-in-molecule perturbation theory first order (IDIM PT1) method have been utilized to construct potential energy surfaces (PESs) for the complex valence, and IP states. Calculated spectroscopic characteristics of the NelCl $(E,\beta)$ and valence states are similar to experimental ones. We calculated energies of the vdW mode and the action NelCl($A$, $v_A$, $n_A\leftarrow X0^+$, $v_X=0$, $n_X$) as well as excitation NelCl ($E$, $v_E=0$, $n_E\leftarrow A$, l3, $n_A$), NelCl ($\beta, v_\beta=0, n_\beta\leftarrow A$, l3, $n_A$) spectra. Calculated excitation and action spectra describe the principal features of experimental spectra. We achieved satisfactory descriptions of the NelCl ($E,0\rightarrow X$), NelCl ($D',0\rightarrow A'$) and NelCl ($\beta,0\rightarrow A$) luminescence spectra using Heidelberg MCTDH method, also.