Hard-X-Ray-Induced Multistep Ultrafast Dissociation.

Area of Science:

• Atomic and Molecular Physics
• Physical Chemistry
• Quantum Dynamics

Background:

• Core-level excitations in molecules can initiate complex relaxation dynamics.
• Ultrafast processes following core ionization are crucial for understanding molecular stability and reactivity.

Purpose of the Study:

• To demonstrate a general mechanism for multistep ultrafast dissociation in molecules.
• To investigate the role of intermediate core-hole states in fragmentation dynamics.

Main Methods:

• Theoretical modeling of core-level excitation and subsequent electronic decay cascades.
• Simulation of nuclear dynamics on potential energy surfaces of intermediate states.

Main Results:

• Creation of deep core holes (τ≤1 fs) triggers rapid relaxation and nuclear dynamics.
• HCl dissociation following Cl 1s→σ* excitation proceeds via multistep ultrafast fragmentation.
• Intermediate states with holes in shallower shells facilitate rapid dissociation.

Conclusions:

• Multistep ultrafast dissociation is a general pathway following hard x-ray absorption.
• The repulsive nature of intermediate state potential energy surfaces drives rapid molecular fragmentation.