Field-free molecular orientation by delay- and polarization-optimized two fs pulses

Area of Science:

• Physical Chemistry
• Molecular Physics
• Ultrafast Spectroscopy

Background:

• Molecular structural information is often lost due to averaging over rotational states.
• Controlling macroscopic directional properties of polar molecules is crucial for detailed analysis.

Purpose of the Study:

• To investigate a two-pulse laser technique for controlling molecular alignment and orientation.
• To explore the effectiveness of a cross-polarized second pulse in enhancing molecular orientation.

Main Methods:

• Utilizing two femtosecond (fs) laser pulses with optimized delay.
• The first pulse induces molecular alignment.
• The second, cross-polarized pulse selectively orients aligned even-J states.

Main Results:

• The two-pulse technique significantly enhances the net degree of molecular orientation.
• Cross-polarization of the second pulse further improves orientation.
• Excellent temporal synchronization between alignment and orientation was achieved.

Conclusions:

• The cross-polarization method offers enhanced control over molecular orientation.
• This technique is promising for ultrafast molecular spectroscopy in a molecule-fixed frame.
• Improved confinement of molecules in the laboratory frame facilitates precise studies.