After so much hard work that paid off, Dr. Joan Dreiling has officially completed her PhD! Munir and Eric have graduated as well! We're so proud of all of them!

The musty smells of Brace Hall have been replaced by the technological scents of Jorgensen! Although Brace has been the home of the Gay lab for many years, we have officially moved into the newly constructed Jorgensen Hall. With a larger space, the lab can be more dynamic than ever! Now that we're all nestled in, you can glance at the new Gay universe:

Our hard-working grad student, Joan Dreiling, gives us a little glimpse into her world, and the exciting project she's been working on, rubidium optical pumping:

Optical Pumping of Mixtures of Rb vapor and N₂ Buffer Gas

"Using the experimental setup shown in Fig. 1, we have studied the optical pumping of mixtures of Rb vapor and N₂ buffer gas. As the frequency of the right-hand circularly-polarized (σ⁺) laser is varied across the D1 absorption profile, the electron spin polarization of the Rb, P_e, is found to take on negative values for small negative values of pump detuning from the absorption profile center (see Fig. 2).

Fig. 2: a) Absorption scan of probe in Rb reference cell. b) Positions of hyperfine transitions, from left to right: 87Rb Fg = 2 → Fe = 1, 87Rb 2 → 2, 85Rb 3 → 2, 85Rb 3 → 3, 85Rb 2 → 2, 85Rb 2 → 3, 87Rb 1 → 1, 87Rb 1 → 2. c) Measured and calculated polarization of Rb vapor as a function of pump laser frequency. Blue data: 10 Torr N2, 4.3 • 1012 cm-3 Rb; solid curve: 10 Torr N2, 99.5% light polarization; dashed curve: 10 Torr N2, 99.95% light polarization. Green data: 1.0 Torr N2 and 8.8 • 1012 cm-3 Rb; curve: 1.0 Torr N2 and 99.5% light polarization. Red data: 0.1 Torr N2, 8.4 • 1012 cm-3 Rb density; curve: 0.1 Torr, 99.5% light polarization.

The spin reversal phenomenon is due to the underlying hyperfine structure of the optically-pumped Rb vapor. This can be understood by considering the Zeeman structure of ⁸⁵Rb (Fig. 3). When F < I+J, the expectation value of P_e for a given eigenstate of the hyperfine Hamiltonian is proportional to -m_F. Thus, for ⁸⁵Rb, if one could selectively populate the ²S_1/2 F = 2 state with m_F > 0, the polarization of the hyperfine-averaged J-states of the atom would exhibit P_e < 0. To achieve this by pumping the F = 3 --> F = (2,3) transition, however, requires a non-σ⁺ component of the pump laser polarization that can drive vertical or left-going absorptions in order to eliminate population of the F = 3, m_F = +3 dark state.

We have modeled these effects with rate equations for the individual F, m_F ground- and excited-state sublevels for ⁸⁵Rb and ⁸⁷Rb. The predictions of the model are depicted as the solid-line curves in Fig. 2c with the fit parameters of laser power 100 mW and the fraction of left-hand circularly-polarized (σ ^-) light is 0.5%. The model gives reasonable agreement with the data. The dashed-line curve shows the results for 10 Torr with the fraction of σ ^- light equal to 0.05%. As the data sets were taken on different days, the waveplate may have been set slightly differently for the 10 Torr data set or experienced a small rotation around the vertical axis, which would yield different polarizations at the respective optimal settings."

~Joan Dreiling, Jorgensen Laboratory of Physics

Did you notice the date? 8, 9, 10! :D

Updates: The Graduates of the Gay Group page is fully updated, so you can see where all those who worked with Dr. Gay ended up. Soon to come will be a page about Joan's interesting project working with rubidium optical pumping. Of course, that's when she's not also working on her other project with chiral (non-imposable mirror-image) molecues: here's a description and visual of that.
Real News: Jimmy's last day at the lab is tomorrow! :( Check out his completed work.

Updates: Check out the updates in the Inmates section. Plus stay tuned for a list of all the undergraduates of the group and where they are today, just in case you were beginning to abandon all hope.

Real news: We have been joined by Dr. Vola Andrianarijaona. Dr. A is originally from Madagascar, although he comes here by way of Paris, Belgium, and Germany (not necessarily in that order). Stay tuned for his CV, which will be online any day now. Also, we have a new undergrad: Jeff Thomas.

Jon has gone through and removed every one of his pictures from the website. I'm going to allow this, because a) he'll be leaving soon anyway b) I can't really do anything about it c) he explains that he's afraid of teenage stalkers, government conspiracies, and UFOs. For a more in-depth explanation of Jon's views on photographs and life in general, he refers you to this helpful, illuminating website.

Real News: Umm...happy summer? Jon and Nick graduated, but they're still with us for the time being.

Updates: Welcome to our newest group member Josh Machacek!

Real News: A little while ago (ok, maybe like a month ago) we got a visit from the "women in science" folks. They toured our labs while we scouted for future victims - er, employees.

Updates: Powerpoints about Jack and Amanda's projects have been put up. Check out the Projects page. We also have a group picture and a picture of our newest member, Xumin.

Real News: ....

Rocker Tommy Lee stopped by UNL to film his reality TV Show. He also enlisted Dr. Gay's invaluable help as an advisor.

They got on famously.

As far as updates, the Graduates page has been updated, so you can now see where most of the graduates work.

Dr. Gay has published his new book. Go to "The Gay Group Stoops to Popularizing Science" [Football Physics] section for more.

Adam Green's thesis work has recently been published in Physics Review Letters. Check the Recent Publications section for the citation and PDF copy.

Justin Zohner has been awarded his Master's, and now has a job in San Antonio. He just goes to show that students can get cool jobs working with secretive high-energy lasers.

Renovations to Brace Labs have begun, and will likely last the summer. A new entrance and more lab space will be added to the building. Unfortunatley, construction also means that my nerves will be tested... darn pile driving...

An FFT of the noise created in the grad offices thanks to the incessant pile driving.

The vibrations as seen in JB's coffee cup. Note how the shape of the cup creates distinct wave patterns, much like electrons in a quantum corral.

Archived: January 2020