Dressed spin of polarized {sup 3}He in a cell

We report a measurement of the modification of the effective precession frequency of polarized {sup 3}He atoms in response to a dressing field in a room-temperature cell. The {sup 3}He atoms were polarized using the metastability spin-exchange method. An oscillating dressing field was then applied perpendicular to the constant magnetic field. Modification of the {sup 3}He effective precession frequency was observed over a broad range of the amplitude and frequency of the dressing field. The observed effects are compared with calculations based on quantum optics formalism.