Nonadiabatic coupling and vector correlation in dissociation of triatomic hydrogen

Abstract

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*.

Quantum-mechanical definition of atoms and their mutual interactions in Born-Oppenheimer molecules

“…Such results, even in the absence of curve crossings in the simple case of symmetric collinear triatomic hydrogen reported here, are seen to be significantly more complex than the better-known cases of the entangled limits of homo-nuclear diatomic systems [92][93][94][95][96][97][98][99][100][101][102][103]. Since such three-body dissociations can be achieved experimentally in various ways under appropriate conditions [117][118][119][120][121], an ensemble of measurements of the internal electronic energies of entangled atomic fragments produced by coherent dissociation of polyatomic molecules can potentially report such atomic state distributions for comparisons with theoretical predictions made on basis of the present or other valid computational approaches.…”

“…Although the ground state of triatomic molecular hydrogen is not a chemically stable compound, its threebody photodissociation has been well studied employing stable H + 3 ions in conjunction with electron pick-up methodolgies [117][118][119][120][121]. Accordingly, the present predictions, reporting atomic-state entanglements having potentially measureable consequences in a simple wellstudied triatomic molecule, would seem to provide an opportunity for corresponding experimental studies.…”

“…Additional calculation of atomic promotion and interaction energies in low-lying triatomic hydrogen states not reported here, which include three-body dissociation pathways relevant to Dalitz plot geometries conveniently accessible to experimental observations [117][118][119][120][121], have been reported separately elsewhere [91]. These calculations include in particular symmetric C 3v triatomic dissociations particularly well-suited for experimental observation in view of the corresponding equilibrium stucture of the precursor H + 3 ion.…”

Quantum-Mechanical Definition of Atoms and Chemical Bonds in Molecules

“…The possibility of measuring atomic entanglements of the electronic states of atoms produced upon coherent dissociation of triatomic molecular hydrogen (H 3 → H + H + H) [90][91][92][93][94], reported here in the symmetric collinear case, can provide a first step in measuring a property of an atom in a molecule as carried by Schrödinger entanglement into the asymptotically-large separation limit. In view of the well-known hydrogenic Coulombic degeneracy, predictions of the 2s,2p, 3s,3p,3d,... compositions of such atomic states cannot be made on basis of calculation in the large-separation limit alone and require an approach which can predict compositions of degenerate atomic states as carried from the interaction zone to asymptotic separation limits.…”

Concluding remarks

“…18,[20][21][22] Novel multi-dimensional imaging and coincidence measurements provide hitherto inaccessible information about product state correlations. 18,23,24 So vast is the array of experimental tools that are now being used to probe the dynamics of non-adiabatic processes that it is not possible to represent all of them in so short a meeting as this. For example, quantum information processing with atomic, molecular or solid-state qubits is an emerging area in which non-adiabatic dynamics and decoherence play intimate roles.…”