Last Saturday, Liz was hooded by Craig as a (soon-to-be) Doctor of Philosophy! The ceremony was held at the Bren Events Center and honored the hard work and achievements of the class of 2017. Craig did a great job with the hooding (no hats were knocked off!) and everyone’s efforts were rewarded with a champagne reception following the event.
Last week Craig and Sara traveled to Chicago for the 10th International Conference on Chemical Kinetics hosted by the University of Illinois at Chicago. This 4-day conference featured talks from many different areas of research including pyrolysis, catalysis, and atmospheric chemistry.
Sara presented a poster on the reactions of the simplest Criegee intermediate with inorganic acids and alcohols:
They also had many opportunities to try the fantastic food Chicago has to offer, and highly recommend the cheeseburger with egg and bacon at Au Cheval.
They also visited The Bean!
Our latest paper, exploring the photochemistry of acetaldehyde to form CH3 + HCO across a broad range of wavelengths, has been published in PCCP. We used a combination of time-resolved ion imaging, with nanosecond and picosecond pulsed lasers, and photofragment excitation action spectroscopy to identify three distinct dissociation mechanisms. At long wavelengths, dissociation occurs statistically on the S0 surface after many tens of nanoseconds. Dissociation at intermediate wavelengths is dominated by relatively fast dissociation on the T1 surface, leading to fast-moving CH3 radicals. At short wavelengths, a new pathway opens that is assigned to dissociation on the S0 surface, accessed via a conical intersection.
The article can be accessed here: 10.1039/c7cp02573d
Our building, Rowland Hall, was dedicated as a National Historic Chemical Landmark by the ACS on April 18th, in recognition of the Nobel Prize-winning work performed there by Sherry Rowland and Mario Molina that identified the role of chlorofluorocarbons in stratospheric ozone loss. A two-day symposium was held at the Beckman Center on April 18th–19th to mark the occasion, featuring distinguished guest speakers from academia, and local AirUCI contributions. Kara and Saswata Roy from Prof. Filipp Furche’s group gave a great joint TED-style presentation explaining how a combination of experiment and theory can provide insights into molecular photochemistry.
On May 12th, we attended the 34th Informal Symposium on Kinetics and Photochemical Processes in the Atmosphere held at UCSD. I gave a talk describing some of our work on the reactions of Criegee intermediates with trace atmospheric gases, Sara presented a poster on the same, and Kara
loitered networked. Aside from learning some exciting new science, we also discovered that the tacos at Puesto in La Jolla are excellent.
Finally, we bade a fond farewell to Ben who has moved on to pastures new. This month he begins a post-doctoral position at Lawrence Berkeley National Lab, working with Dr. Oliver Gessner and Prof. Steve Leone in the Ultrafast X-Ray Science Laboratory. We wish him all the best in the Bay Area and have no doubt that he will be tremendously successful there.
Last week Craig, Kara, and Liz traveled to Asilomar, CA to attend the Pacific Conference on Spectroscopy and Dynamics 2017. Luck was on our side and we were not swept away by a tsunami or mudslide!
In the poster sessions Craig and Kara presented “Competing Pathways in the Near-UV Photochemistry of Acetaldehyde” and “UV photodissociation dynamics of CHI2Cl and its role as a photolytic precursor for a chlorinated Criegee intermediate”.
Liz presented a talk entitled “Direct Kinetics Measurements and Atmospheric Implications of the Reactions between Criegee Intermediates and Tropospheric Pollutants”.
Congratulations to Ben, who gave a great presentation and successfully defended his thesis yesterday!
[Photo credit: Stacey Hughes]
We have been awarded $396,693 by the Chemistry Divison of the National Science Foundation for a three-year project titled, “Unravelling Unconventional photochemistry using time- and state-resolved imaging.” The grant will support our fundamental photochemistry research, in which we use velocity-map ion imaging to explore ‘unusual’ photochemical mechanisms in small molecules.
Our new paper published in J. Phys. Chem. A uses PHOtoFragment EXcitation (PHOFEX) spectroscopy to pick apart the first absorption band of OCS, the most abundant sulfur-containing molecule in the atmosphere. The PHOFEX spectra obtained probing electronically excited S(1D) and ground state S(3P) atoms are distinctly different; the former is broad and unstructured, while the latter shows distinct resonances that can be attributed to vibrational structure following direct excitation of a quasi-bound triplet state.
The article can be found here: 10.1021/acs.jpca.6b06060
Our new paper on the kinetics of reactions between the simplest Criegee intermediate, CH2OO, and the inorganic acids HCl and HNO3 has been published as a “hot paper” in Angewandte Chemie International Edition. The reaction with HNO3 in particular is likely to be an important sink in polluted environments. You can read it here: 10.1002/anie.201604662
UPDATE: A news article highlighting our paper has been published on ChemistryViews.