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SUMMARY:Organic Chemistry in the Air
LOCATION:Chemistry A101
TZID:America/Denver
DTSTART:20261104T160000
UID:2026-10-27-07-02-45@natsci.colostate.edu
DTSTAMP:20261027T070245
Description:Seminar Abstract:\nVolatile organic compounds (VOCs) are emitte
 d into air from diverse biogenic and anthropogenic sources including direc
 t emission from plants\, fossil fuel combustion\, industrial processes\, a
 nd wildfires. They are present in the air we breathe in minute concentrati
 ons\, but exert an outsized impact on atmospheric composition\, air qualit
 y\, and climate. VOCs themselves can be toxic\, but their most widespread 
 consequences come about through their chemistry\; oxidation chemistry in t
 he atmosphere leads to the production of tropospheric ozone\, a deadly and
  highly regulated pollutant\, secondary organic aerosol\, a key component 
 in atmospheric particulate matter with deleterious effects on health and a
  complex influence on global climate\, and CO2\, the most important atmosp
 heric climate forcer. Both the composition of the suite of VOCs in the atm
 osphere\, and the downstream reaction networks that govern their evolution
  in air\, are highly complex\, and remain uncertain. My research group lev
 erages advanced instrumentation\, mechanistic models\, and controlled labo
 ratory experiments to unravel the composition of organics in air and detai
 l the mechanisms that govern their evolution. VOC oxidation networks proce
 ed through a series of reactive intermediates: short lived species that ac
 t as the key branch points in these networks and ultimately determine prod
 uct distributions. The peroxy radical\, RO2\, is arguably the most importa
 nt branch point in these oxidation networks\, with a fate that depends on 
 both the structure of the RO2 and on local reactivity conditions. In labor
 atory experiments\, not all RO2 fates that are important in the atmosphere
  are equally accessible. Thus\, parts of reactivity space remain underexpl
 ored\, leaving gaps in our mechanistic understanding and making it impossi
 ble to correctly account for the effects of RO2 chemistry on atmospheric c
 omposition in models. My group has developed a new approach to laboratory 
 studies of RO2 chemistry\, leveraging alkyl iodide photolysis as a means t
 o produce RO2 in an environmental chamber in the absence of an oxidant sou
 rce. This affords greater control over RO2 fate than traditional\, oxidant
 -initiated experiments\, and permits access to previously unexplored areas
  of RO2 chemical space. We demonstrate that existing mechanistic descripti
 ons fail under these unexplored reactivity regimes\, even for simple\, pro
 totypical RO2. Conditions that access mixed RO2 fates lead to unexpected p
 roducts\, stymie existing mechanistic explanations\, and point towards the
  critical role that poorly-constrained RO2 cross-reactions play in determi
 ning product distributions. In separate work\, we take our instrumentation
  out of the lab and into the world\, measuring ambient air composition at 
 UCLA in the immediate aftermath of the unprecedented Palisades and Eaton w
 ildfires of January 2025. The result is a one-of-a-kind dataset that begin
 s to unravel the impacts that wildland-urban interface (WUI) fires exert i
 n urban air\, providing information beyond what we can glean from regulato
 ry monitors on the air quality impacts of such events. Related ongoing wor
 k is focused on understanding the impacts of smoke on indoor air quality a
 nd human health. This work spans atmospheric organic chemistry across scal
 es\; from fundamental chemical mechanisms to real-world atmospheric comple
 xity\, enabling a more predictive understanding of how reactive organic ch
 emistry shapes the air we breathe.\n\nSpeaker Bio:\n\nVictoria Barber is a
 n Assistant Professor at UCLA in the Department of Chemistry and Biochemis
 try\, with a courtesy appointment in and the Department of Atmospheric and
  Oceanic Sciences. She earned her B.A. in Chemistry from Swarthmore Colleg
 e and her Ph.D. in Physical Chemistry from the University of Pennsylvania\
 , where she worked with Marsha Lester on the spectroscopy and dynamics of 
 Criegee intermediates. As a postdoctoral associate at MIT with Jesse Kroll
 \, she studied peroxy and alkoxy radical chemistry and the effects of air 
 cleaning technologies on indoor air quality. Her group at UCLA takes a mol
 ecular approach to understanding the organic chemistry of outdoor and indo
 or air\, with a particular focus on the chemical mechanisms that govern th
 e oxidation of VOCs in the atmosphere.  4:00 pm
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