Pump-probe spectroscopy of chiral vibrational dynamics

Area of Science:

• Molecular spectroscopy
• Chirality studies
• Quantum chemistry

Background:

• Planar molecules can exhibit transient chirality during out-of-plane vibrations.
• Standard infrared laser excitation of these vibrations in randomly oriented molecules yields no net chiral signal due to phase cancellation.
• Breaking this symmetry is crucial for observing and measuring molecular handedness.

Purpose of the Study:

• To propose a novel pump-probe spectroscopy method for observing time-dependent molecular chirality.
• To demonstrate the feasibility of this technique using quantum-chemical theory.
• To overcome the symmetry limitations in detecting chiral signals from vibrating molecules.

Main Methods:

• Exciting molecular vibrations using a Raman transition in the presence of a static electric field to break symmetry.
• Probing time-dependent net molecular handedness via photoelectron circular dichroism using extreme ultraviolet ionization.
• Utilizing quantum-chemical theory for theoretical validation and simulation.
• Applying the method to carbonyl chlorofluoride as a model system.

Main Results:

• The proposed method successfully breaks the symmetry that cancels chiral signals.
• Time-dependent net handedness of vibrating molecules can be probed.
• Quantum-chemical calculations support the feasibility of the proposed spectroscopic technique.
• The method is shown to be applicable to molecules like carbonyl chlorofluoride.

Conclusions:

• A feasible experimental approach for observing transient molecular chirality is presented.
• The technique overcomes previous limitations in detecting chiral signals from vibrating molecules.
• This method opens new avenues for studying molecular handedness dynamics with current technology.