Relativistic energy transfer.

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Relativistic Quantum Mechanics

Background:

• Energy transfer is fundamental but typically studied at small to intermediate scales.
• Relativistic effects at large energies significantly alter energy transfer dynamics.
• Interatomic Coulombic Decay (ICD) is a key process at high energies, leading to environmental ionization.

Purpose of the Study:

• To investigate the efficiency of large energy transfer involving relativistic effects.
• To analyze the interatomic Coulombic decay (ICD) process at high energies.
• To derive theoretical expressions for ICD amplitude and energy transfer rates.

Main Methods:

• Utilized the Dirac-Breit Hamiltonian for relativistic calculations.
• Derived asymptotic expressions for ICD amplitude using perturbation theory.
• Expanded the Coulomb-Breit interaction in powers of inverse distance.
• Analyzed expressions in both Feynman and Coulomb gauges.

Main Results:

• Derived equivalent expressions for ICD amplitude in different gauges.
• Showed that ICD energy transfer can be highly efficient at long range when donors are embedded.
• Demonstrated that ICD can quench X-ray emission, dominating over Auger decay due to short radiative lifetimes (attosecond regime).

Conclusions:

• Large energy transfer via ICD is efficient, particularly in condensed environments.
• The dominance of X-ray emission and ICD over Auger decay is a hallmark of high-energy processes.
• Understanding ICD is crucial for predicting energy transfer dynamics in various physical and chemical systems.