About the existence of the exotic molecular ions $(HeH)^{2+}$ and $He_2^{3+}$ in a strong magnetic field

Abstract

The Coulombic systems $(\al p e)$ and $(\al\al e)$, $(\al p p e)$, $(\al \al p e)$ and $(Li^{3+} Li^{3+} e)$ placed in a magnetic field $B \gtrsim 10^{11} {G}$ are studied. It is demonstrated a theoretical existence of the exotic ion $(He H)^{2+}$ for $B\gtrsim 5\times 10^{12} {G}$ in parallel configuration (the magnetic field is directed along internuclear axis) as optimal as well as its excited states $1\pi, 1\delta$. As for the exotic ion ${He}_{2}^{3+}$ it is shown that in spite of strong electrostatic repulsion of $\al-$particles this ion can also exist for $B \gtrsim 100 {a.u.} (= 2.35\times 10^{11} {G})$ in parallel configuration as optimal in the states $1\si_g$ (ground state), $1\pi_u, 1\delta_g$. Upon appearance both ions are unstable towards dissociation with $He^+$ in the final state but with very large lifetime. However, at $B\gtrsim 10000$ a.u. the ion $(He H)^{2+}$ becomes stable, while at $B\gtrsim 1000$ a.u. the ion ${He}_{2}^{3+}$ becomes stable. With a magnetic field growth, both exotic ions become more and more tightly bound and compact, their lowest rotational and vibrational energies grow. At the edge of applicability of non-relativistic approximation, $B \sim 4.414 \times 10^{13}$ G, there are indications that three more exotic linear ions $(H-He-H)^{3+}$, $(He-H-He)^{4+}$ and even $Li_2^{5+}$ in parallel configuration may also occur.