Multidimensional characterization of the conical intersection seam in the normal mode space

Area of Science:

• Chemical Physics
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• Conical intersections are critical in photochemistry, mediating nonadiabatic transitions between electronic states.
• Understanding the structure and dynamics of these seams is essential for controlling chemical reactions.
• Predissociation in molecules like thioanisole provides a window into these ultrafast processes.

Purpose of the Study:

• To characterize the multidimensional conical intersection seam in thioanisole isotopomers.
• To investigate the influence of vibronic eigenstates on nonadiabatic transition probabilities.
• To elucidate the structure and dynamic character of the conical intersection seam via H/D substitution.

Main Methods:

• Experimental observation of dynamic resonances in nonadiabatic transition probabilities during thioanisole isotopomer predissociation.
• Analysis of Herzberg type-I (electronic) and type-II (vibrational) predissociation pathways.
• Utilizing partial or full H/D substitution to modify the molecular normal mode space.
• Supporting experimental findings with theoretical calculations of potential energy curves.

Main Results:

• The nonadiabatic bifurcation of reactive flux is strongly dependent on the quantum nature of the S1/S2 vibronic eigenstate.
• H/D substitution allows characterization of the conical intersection seam from multiple perspectives.
• Experimental observations provide essential information on the structure and dynamics of the conical intersection seam.
• Theoretical calculations corroborate the experimental findings.

Conclusions:

• The study successfully characterized the multidimensional conical intersection seam in thioanisole.
• Vibronic eigenstates and isotopic substitution are key factors in controlling nonadiabatic dynamics.
• This work offers insights into the interplay between molecular structure and reaction pathways at conical intersections.