We report on the multiphoton ionization and dissociation of hydrogen and deuterium molecules in intense (8×${10}^{11–}$4×${10}^{13}$ W/${\mathrm{cm}}^2$) laser fields. The investigations were performed with the second harmonics of two different laser systems, a 50-ps neodymium-doped yttrium lithium fluoride and a 10-ns neodymium-doped yttrium aluminum garnet laser. Measurements included energy-resolved photoelectron and mass spectroscopy. In addition, we report on a measurement of the dynamics of different above-threshold dissociation branching ratios for ${\mathrm{H}}_2^{+}$ and ${\mathrm{D}}_2^{+}$ over a wide range of laser intensities. Our results support the dressed-molecule picture at least qualitatively, but differences do exist with the quantitative predictions.

• Received 12 March 1991

DOI:https://doi.org/10.1103/PhysRevA.44.R1458