Optical multiple resonance spectroscopy of H2, D2, and HD

Using optical multiple resonance spectroscopy, we observed the complex bound levels and the quantum interference structure of H2, D2, and HD in the second dissociation energy limit. A newly developed detection scheme gave remarkable high-resolution spectra up to approximately 50 MHz due to a reduction in the power for the probe and the detection lasers. The perturbed bound structure without the rovibrational progression was observed due to long-range nonadiabatic couplings between the B, B', and C states of the hydrogen molecule. The Lorenzian line shape of the last bound level in D2 was deconvoluted and the AC Stark effects were reduced to give the true line shape of the level. The natural lifetime of this level showed strong predissociative characteristics and corresponded to a width of 315.1 MHz. An accurate determination of the energy for the intermediate level will give us an accurate dissociation energy for the ground electronic state of the hydrogen molecule