We have observed protons with near-zero kinetic energy that originate from
the interaction of a frequency tripled (lambda = 266 nm), 250 fs intense Ti
:sapphire laser with H-2 molecules. These protons are tentatively ascribed
to zero-photon dissociation (ZPD) of H-2(+). Earlier quantum mechanical cal
culations show that such a process should occur due to the partial escape o
f the vibrational wavepacket that is trapped in the laser-induced, adiabati
c well above the one-photon crossing of dressed Floquet states. The fact th
at slow protons are also observed at the second harmonic (lambda = 400 nm),
but to a lesser extent, is consistent with the ZPD explanation.