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Coherent radiation from neutral molecules moving above a grating.
Alexey Belyanin1, Vitaly Kocharovsky, Vladimir Kocharovsky
1Physics Department and Institute for Quantum Studies, Texas A&M University, College Station, Texas 77843-4242, USA. belyanin@atlantic.tamu.edu
Physical Review Letters
|February 28, 2002
Summary
We predict parametric self-induced excitation in molecules moving over periodic gratings. This instability can generate detectable coherent radiation, offering a novel radiation mechanism distinct from existing methods.
Area of Science:
- Molecular physics
- Quantum optics
- Electromagnetism
Background:
- The study of radiation mechanisms for molecules moving over periodic structures is crucial for developing new coherent radiation sources.
- Existing mechanisms like Smith-Purcell and transition radiation involve moving charges and their oscillating images, creating oscillating dipoles.
- Understanding instabilities in molecular dipole oscillations is key to harnessing novel radiation phenomena.
Purpose of the Study:
- To predict and investigate the phenomenon of parametric self-induced excitation in molecules moving above periodic dielectric or conducting media.
- To elucidate the role of radiation reaction force in modulating molecular transition frequencies and inducing parametric instability.
- To differentiate this novel instability mechanism from established phenomena like Smith-Purcell and transition radiation.
Main Methods:
- Theoretical prediction and analysis of molecular dynamics above a periodic grating.
- Modeling the effect of radiation reaction force on molecular transition frequencies.
- Investigating the onset and characteristics of parametric instability from quantum or thermal fluctuations.
Main Results:
- Parametric self-induced excitation of molecules moving over periodic gratings was predicted.
- The radiation reaction force was shown to modulate molecular transition frequencies, leading to instability.
- A novel instability mechanism for electrically neutral molecules was identified, distinct from charge-based radiation processes.
- The potential for parametrically excited molecular bunches to produce detectable coherent radiation flux (up to microwatts) was demonstrated.
Conclusions:
- Parametric self-induced excitation offers a new pathway for generating coherent radiation from molecular systems.
- This mechanism provides an alternative to charge-based radiation processes, applicable to neutral molecules.
- The predicted coherent radiation flux is potentially detectable, opening avenues for experimental verification and applications.