Ultrafast angular momentum orientation by linearly polarized laser fields

Area of Science:

• Physical Chemistry
• Quantum Optics
• Molecular Dynamics

Background:

• Controlling molecular motion at the quantum level is crucial for advanced applications.
• Ultrafast laser pulses offer precise tools for manipulating molecular states.
• Achieving directional molecular rotation is a significant challenge in molecular physics.

Purpose of the Study:

• To theoretically demonstrate and experimentally verify a method for creating oriented molecular ensembles.
• To achieve ultrafast (picosecond timescale) control over molecular rotational angular momentum.
• To explore the quantum interference effects responsible for directional molecular orientation.

Main Methods:

• Utilizing a pair of linearly polarized intense femtosecond laser pulses.
• Precisely controlling the time delay and mutual polarization between the laser pulses.
• Analyzing quantum interference between rotational wave packets generated via stimulated Raman excitation.

Main Results:

• Demonstrated the creation of molecular ensembles with oriented rotational angular momentum.
• Achieved ultrafast orientation on the picosecond timescale.
• Observed asymmetric population distributions in magnetic sublevels (+M and -M) due to quantum interference.
• Generated spatiotemporally propagating molecular ensembles exhibiting directional rotation.

Conclusions:

• The proposed method effectively controls molecular orientation on ultrafast timescales.
• Quantum interference is the key mechanism enabling directional molecular rotation.
• This technique provides a novel way to generate rotating molecular ensembles with classical perspectives of clockwise or counterclockwise motion.