Highlighting the angular dependence of bond softening and bond hardening of H+2 in an ultrashort intense laser pulse

Measurements of laser-induced dissociation of H+2 by 135 fs 790 nm pulses with a peak intensity of approximately 2.4 x 1014 W cm-2 reveal a strong correlation between the angular distribution and the kinetic energy released upon dissociation. This correlation is highlighted by comparing the measured angular distribution to the one expected for photo-dissociation in the weak-field limit which has a cos2θ distribution. Bond softening is aligned along the laser polarization much more than weak-field photo-dissociation. In contrast, bond hardening results in wider angular distributions than photo-dissociation. The deviation of these angular distributions from cos2θ increases with the energy difference from the crossing between the ground 1sσ state potential curve and the one-photon dressed 2pσ diabatic Floquet potential curve. (letter to the editor)