Strong chemical bond of stable He2in strong linearly polarized laser fields

Abstract

The van der Waals complex of the helium dimer has a binding energy of $\ensuremath{\sim}$10${}^{\ensuremath{-}7}$ eV and a bond distance of $\ensuremath{\sim}$52 \AA{}. Our ab initio electronic structure calculations show that in an ac electric field of $\ensuremath{\approx}$$5.614\ifmmode\times\else\texttimes\fi{}{10}^{19}$ W/cm${}^{2}$ with a high photon energy ($\ensuremath{\approx}$108 eV), stable He${}_{2}$ molecules with a binding energy of 12.5 eV, which are much stronger than conventional molecular hydrogen bonds, are produced. The chemical bond distance of He${}_{2}$ produced by the strong laser field is equal to $2.01$ \AA{}. The strength of the chemical bond of He${}_{2}$ is reflected in more than 4500 rovibrational bound states. The strongly bound He${}_{2}$ is aligned by the linear polarized field, like in other diatomic molecules. However, it is shown that the mechanism of the alignment of the He${}_{2}$ molecule produced by light differs from the usual alignment mechanism of real molecules. Our results indicate the possibility of producing unusual chemical species, and perhaps chemical reactions that differ from what we know today, in the presence of strong electromagnetic radiation.