Welcome to our 2025-2026 program year. Our plan for this program year is for a mix of social events, in person Initiation and virtual meetings. We will also have our Undergraduate Research Symposium in February.
Iota Sigma Pi: Aurum Iodide Chapter
Announcement for April 2026 Meeting – Initiation
Meeting Date and Time: Saturday, April 18, 2026
1:00 pm – 4:00 pm
Location: DePaul University (Lincoln Park Campus), Student Center, Room 314AB, 2250 N
Sheffield Ave, Chicago, IL 60614
Menu: Fettucine Pasta, Pesto Primavera Sauce, Alfredo Sauce, Chicken, Shrimp,
salad, Garlic Bread Sticks, Bakery-fresh Brownies, Coffee (caffeinated and decaf) and Tea
Cost: $25 for non-initiates (members and guests)
$12.50 for student non-initiate guests (please indicate in reservation if you are a student)
Free for initiates
RSVP: by Evite or to Tanya Hunter at ispaurumiodide@gmail.com by 12:00 pm Friday, April 10, 2026.
Speaker: Rebecca L. Caravan, Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, (caravarl@anl.gov)
Title: Molecular Weight Growth Reactions of Criegee Intermediates
Abstract: Criegee intermediates (sCIs) are zwitterions formed from the ozonolysis of alkenes. Direct and ozonolysis studies have revealed that many bimolecular reactions of sCIs proceed via insertion mechanisms, forming highly oxygenated reaction products with organic hydroperoxide (ROOH) functionality.[1] Such molecular weight growth processes may contribute to the formation of secondary organic aerosol (SOA): a pollutant which accounts for much of the total atmospheric mass of fine particles.[2] SOA impacts air quality, human health, and the radiative balance of the atmosphere, but their chemical formation pathways are currently not fully understood.
We will present our recent results on the kinetics and mechanisms of sCI molecular weight growth reactions, including an oligomerization sequence initiated by the insertion of CH2OO into formic acid (Figure 1).[3-6] We will discuss the broader implications of this chemistry, making links to atmospheric models and field measurements.
Argonne is supported by USDOE, BES, Division of Chemical Sciences, Geosciences, and Biosciences under Contract No. DE-AC02-06CH11357. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231.
Speaker’s Biography: Rebecca Caravan is a Chemist in the Chemical Dynamics in the Gas Phase Group at Argonne National Laboratory. Her research focuses on the fundamental kinetics and mechanisms of reactive intermediates (such as carbonyl oxide Criegee intermediates and peroxy radicals) and their tropospheric impacts, via direct laboratory studies using both tabletop and synchrotron techniques. Before joining Argonne, she read Chemistry at the University of Bristol, received her PhD from the University of Leeds, was a postdoctoral researcher at Sandia National Laboratories, and an NPP fellow at NASA Jet Propulsion Laboratory.
References
[1] R. Chhantyal-Pun, M.A.H. Khan, C.A. Taatjes, C.J. Percival, A.J. Orr-Ewing & D.E. Shallcross, Int. Rev. Phys. Chem., 39(3), 385-424 (2020).
[2] A.G. Carlton, C. Wiedinmyer & J.H. Kroll, Atmos. Chem. Phys., 9 (14), 4987-5005 (2009).
[3] R.L. Caravan, M.F. Vansco, K. Au, M.A.H. Khan, Y.-L. Li, F.A.F. Winiberg, K. Zuraski, Y.-H. Lin, W. Chao, N. Trongsiriwat, P.J.Walsh, D.L. Osborn, C.J. Percival, J.J-M. Lin, D.E. Shallcross, L. Sheps, S.J. Klippenstein, C.A. Taatjes & M.I. Lester, Proc. Natl. Acad. Sci., 117 (18), 9733-9740 (2020).
[4] R.L. Caravan, T.J. Bannan, F.A.F. Winiberg, M.A.H. Khan, A.C. Rousso, A.W. Jasper, S.D. Worrall, A. Bacak, P. Artaxo, J. Brito, M. Priestley, J.D. Allan, H. Coe, Y. Ju, D.L. Osborn, N. Hansen, S.J. Klippenstein, D.E. Shallcross, C.A. Taatjes & C.J. Percival, Nat. Geo., 17 (3), 219-226 (2024).
[5] C.J. Percival, F.A.F. Winiberg, W. Chao, M. Zou, M.F. Vansco, C.R. Markus, M.A.H. Khan, D.L. Osborn, A.W. Jasper, A. Borkowski, M.I. Lester, D.E. Shallcross, S.J. Klippenstein, C.A. Taatjes, & R.L. Caravan, In Prep. (2026).
[6] M. Zou, F.A.F. Winiberg, M.F. Vansco, C.R. Markus, D.L. Osborn, S.J. Klippenstein, C.A. Taatjes, M.I. Lester, C.J. Percival & R.L. Caravan, In Prep. (2026).
For a map of DePaul University: http://www.depaul.edu/campus-maps/Pages/default.aspx
Please take a moment to pay your yearly dues. You may do so by visiting the National website https://www.iotasigmapi.org/
Interested in becoming a member of Iota Sigma Pi? To find the application criteria and apply for membership, visit the National website at iotasigmapi.org and go to Membership (https://www.iotasigmapi.org/become-a-member).