Experimental and quantum-chemical studies on the three-particle fragmentation of neutral triatomic hydrogen

Dissociation of well-defined H₃ Rydberg states into three ground state hydrogen atoms reveals characteristic correlation patterns in the center-of-mass motion of the three fragments. We present an extensive experimental dataset of momentum correlation maps for all lower Rydberg states of H₃ and D₃. In particular the states with principal quantum number $n=2$ feature simple correlation patterns with regular occurence of mutual affinities. Energetically higher-lying states typically show more complex patterns which are unique for each state. Quantum-chemical calculations on adiabatic potential energy surfaces of H₃ Rydberg states are presented to illuminate the likely origin of these differences. We discuss the likely dissociation mechanisms and paths which are responsible for the observed continuum correlation.