Advanced Undergraduate Laboratory

Department of Physics

University of Toronto

Rb: Optical Pumping in Rubidium

Circularly polarized light from a Rubidium lamp is used to "pump" Rb vapour into a specific m_F level. Isotopic abundance ratios and the g-factor for each level may be calculated. Alfred Kastler won the Nobel Prize in 1966 for the development of optical pumping. Optical pumping was key step in the development of masers and lasers, and underlies many important measurements and methods in atomic and optical physics.

Write-Up in PDF Format or Microsoft Word Format.

(The experiment is currently located in MP242; last write-up revision: October 2018.)

NOTE FOR THIS WRITE-UP(J.Thywissen Mar. 2005)

• When looking for resonances of ⁸⁷Rb and ⁸⁵Rb, try scanning the offset coils in a triangle wave, and keeping the rf frequency constant. (Instead of the suggested approach.) This will require that you calibrate the field produced at a given current in the offset coils.

4^th year Arts and Sciences undergraduate, Lee McNab, working on Optical Pumping in Rubidium

Interesting Note:

4^th-year student Asya Danilova discovered an unpredicted phenomena in the graph of optical pumping signal strength versus vertical field strength.  Resonance Size is expected to rise as the vertical component of the magnetic field decreases toward zero (see step 5 of the Procedure section of the write-up: “Determination of Zero Field”). In a range of -2 to +2 Gauss, a broad maximum around zero is clearly seen. However, Asya discovered that in a narrow range of -0.003 to +0.003 Gauss, a sharp minimum occurs (see two graphs below). A quantitative explanation of this observation has not yet been found.

Asya’s data plotted over the range -1.7 to +1.3 Gauss. The broad maximum is as predicted in the write-up in step 5 of the Procedure section: “Determination of Zero Field”.

Zoom-in of Asya’s data, plotted over the range -0.2 to +0.3 Gauss, with fit.

Last updated on 19 October 2018