Isomerization HCN → HNC in the electronic ground state using chirp-optimized mid-IR pump and dump laser pulses: 3D...

Area of Science:

• Quantum Chemistry
• Chemical Physics
• Laser Spectroscopy

Background:

• The study of molecular dynamics and chemical reactions is crucial for understanding chemical processes.
• Hydrogen cyanide (HCN) is a fundamental molecule with complex dynamics.

Purpose of the Study:

• To systematically derive reduced dimensionality Hamiltonians from a full six nuclear-degrees-of-freedom (6D) Hamiltonian for HCN.
• To achieve laser-induced isomerization of HCN using a pump-dump scheme.
• To optimize laser pulse shapes for efficient molecular control.

Main Methods:

• Derivation of 4D and 3D Hamiltonians from the 6D HCN Hamiltonian.
• Implementation of a pump-dump laser scheme for isomerization.
• Optimization of linear temporal chirps using gradient-based GOAT and stochastic methods.
• Demonstration of vibrational ladder climbing via overtone bending modes.

Main Results:

• Successful laser-induced isomerization of the 3D planar fixed-CN orientation HCN model.
• Optimization of laser pulses using GOAT algorithm and comparison with stochastic methods.
• Demonstration of a partial vibrational ladder climbing mechanism with the pump pulse.
• Population of multiple modes by the dump pulse.

Conclusions:

• The derived laser pulses are experimentally feasible.
• Coherent laser control is effective for steering molecular isomerization.
• The GOAT algorithm provides an efficient method for laser pulse optimization.