Ultra-Long-Range Rydberg Trimers with a Repulsive Two-Body Interaction

A Rydberg and a ground-state atom can form ultra-long-range diatomic molecules provided the interaction between the ground-state atom and the Rydberg electron is attractive [C. H. Greene et al., Phys. Rev. Lett. 85, 2458 (2000)]. A repulsive interaction does not support bound states. However, as we will show, adding a second ground-state atom, a long-range bound triatomic molecule becomes possible.

Figure 1

The adiabatic potential Eq. (7) with $r_1=R$ for the ($n=30$) neon Rydberg dimer (dash-dotteded black line) and the symmetric stretch cuts Eq. (15) of trimer in solid blue line ($+$) and dashed red line ($-$).

Figure 2

The adiabatic potential $V_B(\rho )$ [see Eq. (18)] at the outermost equilibrium point $R_0$ as a function of the bending coordinate $\rho$ for the ($n=30$) neon Rydberg trimer. The solid blue line and the dashed red line correspond to $E_{\mathrm{dia}}^{+}$ and $E_{\mathrm{dia}}^{-}$ in Eq. (11), respectively. The shaded area shows the quantized state.

Figure 3

The adiabatic potential $V_A(z)$ [see Eq. (18)] at the outermost equilibrium point $R_0$ as a function of the asymmetric stretch coordinate $z$ for the ($n=30$) neon Rydberg trimer as well as the corresponding potential for the ${\mathcal{E}}^u$ potential (upper curve).

Figure 4

The contour plot for the lower adiabatic potential surface of the neon Rydberg trimer in collinear configuration. The directions of the symmetric (SS) and asymmetric stretch (AS) modes are indicated. The white dot represents the system at the equilibrium point (850, 0, 0), whose subsequent decay with the combined SS motion in the AS direction is represented by the curly arrow.