H. Rottke et al., H-2-B-(1)SIGMA(-FIELD()(U) PHOTODISSOCIATION IN AN INTENSE INFRARED LIGHT), Journal of physics. B, Atomic molecular and optical physics, 30(12), 1997, pp. 2835-2844
The first experiment on 1064 nm infrared (IR) multiphoton excitation o
f H-2 with single B-1 Sigma(u)(+)(upsilon = 3.J) rotational levels as
initial states is reported. These states are prepared by one-photon ex
citation from the molecular ground state. We investigate the H-2(+) an
d H+ ion yield, the dissociation fraction H+/(H-2(+) + H+) and the Hion kinetic energy distribution as a function of the IR light intensit
y in the range from 5 x 10(9) W cm(-2) up to 7 x 10(11) W cm(-2). The
dissociation fraction depends sensitively on the initial rotational st
ate. Transient resonances induced by AC Stark shifting states seem to
influence the branching ratio between photoionization and dissociation
. The H+ photoion kinetic energy distributions show that the molecule
dissociates after three-photon absorption into H(1s) + H(2l). The H(2l
) atoms are then photoionized. The AC Stark shift of the final dissoci
ation product states H(2l) in the IR light field seems to be responsib
le for a small intensity-dependent shift of the H+ kinetic energy dist
ribution.