Suppressed molecular ionization for a class of diatomics in intense femtosecond laser fields

It is shown that the puzzling experimental observation of suppressed molecu lar ionization, in intense laser fields, of O-2, and its absence in N-2, is a symmetry induced dynamical effect. More generally, it is predicted that the ionization signal of the class of homonuclear diatomic molecules having valence orbitals with an antibonding symmetry (e.g., sigma(u), pi(g)) woul d be suppressed, but not those with a bonding symmetry (e.g., sigma(g), pi( u)). The suppression effect can be visualized as due to an effective destru ctive interference between the two subwaves of the ionizing electron emergi ng from the two atomic centers.