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Alignment Thresholds of Molecules
Joshua E Szekely1, Tamar Seideman1
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Physical Review Letters
|November 14, 2022
Summary
Molecular alignment in laser fields shows a distinct intensity threshold. Below this threshold, molecules are randomly oriented, but above it, they rapidly align, a phenomenon with practical applications in physics and optics.
Area of Science:
- Molecular physics
- Laser-matter interactions
- Quantum optics
Background:
- Molecules align in laser fields, enabling applications in physics and optics.
- Adiabatic alignment dynamics are crucial for controlling molecular orientation.
Purpose of the Study:
- Investigate a previously unexplored phenomenon in molecular adiabatic alignment.
- Describe the physical origin and implications of this phenomenon.
- Analyze the intensity and temperature dependencies of molecular alignment.
Main Methods:
- Theoretical analysis of molecular alignment dynamics.
- Derivation of analytical forms for intensity and temperature dependencies.
- Numerical illustration of the alignment threshold.
Main Results:
- Discovered a threshold behavior in the intensity dependence of molecular alignment.
- Alignment rapidly increases above a specific intensity threshold.
- Intensity and temperature dependencies exhibit universal curves for linear molecules.
- Alignment threshold occurs below the off-resonance ionization threshold.
Conclusions:
- The threshold behavior is attributed to a tunneling mechanism that ceases at the threshold intensity.
- This universal threshold phenomenon in molecular alignment is readily testable experimentally.
- The findings have implications for controlling molecular orientation in laser fields.
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