Profound isotope effect in dissociation of triatomic hydrogen

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Chemical Physics

Background:

• High-lying Rydberg states are crucial for understanding molecular dissociation dynamics.
• External electric fields can significantly influence molecular fragmentation pathways.
• D3 and H3 molecules serve as fundamental systems for studying molecular behavior.

Purpose of the Study:

• To investigate the three-particle dissociation of D3 Rydberg states induced by an external electric field.
• To analyze the momentum vector correlation of fragment center-of-mass motion.
• To compare dissociation geometries of D3 with H3 and dissociative recombination of D3(+) with electrons.

Main Methods:

• Excitation of high-lying Rydberg states in D3 using tunable lasers.
• Application of an external electric field to induce dissociation.
• Measurement of fragment momentum vectors using coincidence detection techniques.
• Analysis of momentum vector correlation maps to determine fragment geometries.

Main Results:

• Observed convergence of momentum vector correlation maps near the ionization threshold.
• Identified two distinct fragment configurations: near linear and symmetric acute angle geometries.
• Compared D3 dissociation with dissociative recombination of D3(+) and H3 dissociation.
• Noted the absence of the acute angle geometry in H3 dissociation.

Conclusions:

• External electric fields lead to distinct dissociation geometries in D3 Rydberg states.
• The observed geometries provide insights into the role of molecular symmetry and field interactions.
• Differences between D3 and H3 dissociation highlight the influence of molecular structure on fragmentation pathways.