Theoretical calculations on electronic transitions for H3, including Rydberg and transition state spectra

Stark field control of nonadiabatic dynamics in triatomic hydrogen

We show experimentally that an external electric field can be used to control the amplitudes of nonadiabatic paths taken by a dissociating molecule. In the example presented here, this control is achieved by Stark-field mixing in H(3) Rydberg states with different decay paths. The final state continuum is in each path formed by three-particle wave packets of slow neutral hydrogen atoms in their electronic ground state. Their momentum vector correlations show signs of interference, since the molecule can access the identical continuum via two distinctly different paths, involving different nonadiabatic coupling mechanisms. As an added feature a preferred alignment of the fragmentation plane in the laboratory frame emerges, corresponding to a selective dissociation of molecules oriented along the field direction.

Nonadiabatic coupling and vector correlation in dissociation of triatomic hydrogen

We determine experimentally the vector correlation among the three neutral ground state hydrogen atoms which appear in dissociation of neutral H3* molecules. The sum of the kinetic energies of the three H-atoms is fixed by selecting the energy of the H3* molecule by laser excitation in the range between 0.85 and 3.60 eV. The highly structured maps of correlation in the motion of the three atoms provide a direct view of the internal molecular couplings which initiate dissociation. We discuss this feature in a model calculation and in terms of a new quantum chemical calculations of the potential energy surfaces of H3*.

Three-body dissociation dynamics of the low-lying Rydberg states of H3 and D3

The dynamics of the three-body dissociative charge exchange of fast (12 keV) H+3 and D+3 with Cs have been studied using multiparticle translational spectroscopy. The observed partitioning of product momenta was found to be state-specific and yields insights into the nuclear motion during dissociation for the three lowest-lying 2s 2A'1, 2p 2A''2, and 3p 2E' metastable Rydberg states of H3 and the 2s 2A'1 and 2p 2A''2 states for D3. These results provide direct empirical information on the nonadiabatic couplings that govern the three-body dissociation of the lowest-lying Rydberg states of H3 and D3.

Maps of nonadiabatic coupling in triatomic hydrogen

We show in an experiment that dissociation of state-selected neutral H3* molecules into three ground-state hydrogen atoms reveals highly structured maps of correlation in the motion of the three atoms. These maps provide a direct view of the internal molecular couplings which initiate dissociation.