In superintense, relatively high-frequency fields, ${\mathrm{H}}_2^{+}$ presents a strikingly different behavior from that found at lower frequencies. By applying the high-frequency Floquet theory of laser-atom interactions, we predict for the ground state progressive alignment of the molecular axis with the direction of a linearly polarized field as the intensity increases and persistence of the bond strength. The energy spectrum undergoes complete restructuring: while the field-free rotational levels become librational, they are gradually promoted with respect to the vibrational ones.

• Received 11 April 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.2039