Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
We are investigating the technique of saturation spectroscopy (two counter propagating photons incident on the same sample). This technique offers the advantage of a Doppler- free spectrum. We currently have a Doppler-broadened linewidth of 400 MHz and we expect a reduction to around 500 kHz. Potentially, this technique can result in a more accurate determination of the velocity shear in the rotation profile of an unneutralized magnesium ion plasma. We are planning to implement a setup based on a Couillaud-Holbrow[1] design. The apparatus uses two antiparallel beams incident on an I_2 cell. One strong beam is used as a pump beam and saturates the iodine molecules in its path. The second weak beam is a probe beam that measures the absorption of the iodine in the saturated area. The third beam is a weak reference beam that measures the absorption in the unsaturated iodine. When the two weak beams are differenced, they will give the absorption spectrum of the hyperfine structure of molecular iodine around \lambda = 560 nm. [1] C.H. Holbrow; B. Couillaud. Hyperfine Interactions, vol.37, p.185-208 (1987). Supported by the National Undergraduate Fellowship Program and ONR grant (N00014-96-1-0239).