High-resolution studies of collision-induced population grating resonances in optical four-wave mixing in sodium vapor
Optical four-wave mixing resonances in sodium vapor induced by collisions with inert buffer gases (He,Ar,Xe,N/sub 2/) are characterized at high resolution (<5 MHz) using lasers tuned near the D lines of Na. These resonances are interpreted in terms of coherent scattering from a population grating established by collisional absorption of the incident radiation. The roles of homogeneous and inhomogeneous contributions to the resonance line shapes are clarified. The line shapes exhibit structure sharper than the predicted linewidth, that characteristic of the 3P-to-3S transition rate. We show that this is caused by collision-induced optical pumping which introduces the ground-state lifetime into the grating relaxation physics. These long-lived gratings are exemplified dramatically by experiments in the presence of N/sub 2/ which collisionally quenches the Na 3P states. Similar results are obtained in Xe where it is argued that excimer formation with the 3P states plays a role in the population dynamics. Model calculations of the effects of sodium level degeneracy on the grating dynamics are presented to support these conclusions. Finally we present data illustrating interference between the collision-induced population grating resonances detailed here and collision-induced coherent Raman resonances between Zeeman sublevels of the ground state.
- Research Organization:
- Division of Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
- OSTI ID:
- 6106747
- Journal Information:
- Phys. Rev. A; (United States), Vol. 30:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARGON
ATOM-ATOM COLLISIONS
HELIUM
NITROGEN
ATOM-MOLECULE COLLISIONS
NONLINEAR OPTICS
SODIUM
OPTICAL PUMPING
XENON
COHERENT SCATTERING
ENERGY-LEVEL TRANSITIONS
GRATINGS
LINE WIDTHS
RESOLUTION
ALKALI METALS
ATOM COLLISIONS
COLLISIONS
ELEMENTS
FLUIDS
GASES
METALS
MOLECULE COLLISIONS
NONMETALS
OPTICS
PUMPING
RARE GASES
SCATTERING
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena