Light-Induced Fano Resonances as an Optical Switch for Isotope-Selective Photodissociation.

Area of Science:

• Physical Chemistry
• Quantum Chemistry
• Laser Spectroscopy

Background:

• Isotope-selective photodissociation offers a route for laser-based separation but is limited by fixed molecular cross sections.
• Achieving high efficiency and selectivity in isotope separation remains a significant challenge in chemical physics.

Purpose of the Study:

• To develop an active optical-switching strategy for dynamically controlling isotope-selective photodissociation.
• To demonstrate the ability to tailor isotopologue-specific Fano resonances for precise molecular separation.

Main Methods:

• Utilized a nonresonant ultraviolet control pulse to generate and tune Fano resonances.
• Coupled high-lying vibrational levels to a dissociative continuum to modulate photodissociation cross sections.
• Employed full quantum wave packet simulations for hydrogen fluoride (HF) and deuterium fluoride (DF) isotopologues.

Main Results:

• Demonstrated reversible switching of photofragment yield ratios by orders of magnitude.
• Showcased the ability to selectively suppress or enhance dissociation of target isotopologues.
• Achieved high spectral precision in controlling molecular photodissociation.

Conclusions:

• Established a versatile and efficient mechanism for isotope-selective photochemistry.
• Opened a pathway toward coherent optical control of molecular photodissociation.
• The active optical-switching strategy provides a novel approach for isotope separation and molecular control.