Selective control over fragmentation reactions in polyatomic molecules using impulsive laser alignment.

Area of Science:

• Physical Chemistry
• Quantum Mechanics
• Molecular Dynamics

Background:

• Controlling chemical reactions at the molecular level is a key challenge in chemistry.
• Ultrafast laser pulses offer precise temporal control over molecular processes.
• Understanding dissociation and isomerization pathways is crucial for reaction control.

Purpose of the Study:

• To investigate molecular alignment as a method for controlling reaction pathways in polyatomic molecules.
• To demonstrate control over individual reaction pathways using femtosecond laser pulses.
• To explore the role of inner valence orbitals in controlled ionization and subsequent reactions.

Main Methods:

• Utilizing ultrafast laser pulses (few-femtoseconds) to ionize and align polyatomic molecules.
• Employing acetylene (C2H2) as a model system for studying fragmentation and isomerization.
• Analyzing the influence of molecular axis alignment relative to laser polarization on reaction outcomes.

Main Results:

• Molecular alignment successfully controlled the relative probabilities of individual reaction pathways.
• Both enhancement and suppression of specific fragmentation channels were achieved.
• Control over dissociation and isomerization pathways was linked to selective population of excited electronic states via inner valence orbital ionization.

Conclusions:

• Molecular alignment is a viable strategy for steering chemical reactions in polyatomic molecules.
• Precise control over reaction dynamics can be achieved by manipulating electronic state populations through ionization.
• This approach opens new avenues for targeted chemical synthesis and manipulation at the femtosecond timescale.