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Physical Chemistry Seminar Series: Krishna Foster (The California State University) – on Zoom
March 29, 2022 | 4:00 pm - 5:00 pm
About the Speaker:
Dr. Foster was awarded a B.S. in chemistry from Spelman College in 1992 and a Ph.D. in physical chemistry from the University of Colorado at Boulder in 1998. Her postdoctoral research conducted at the University of California, Irvine and in the high-Arctic, resulted in two Science Magazine publications. She joined the faculty of California State University, Los Angeles in 2000 and is currently a Full Professor of Chemistry. She resides in Altadena, California.
Her research interests include determining the role of polycyclic aromatic compounds on the oxidizing capacity of the lower atmosphere; identifying reduced phosphorus oxyanions in natural environments, and chemical education. She has co-authored 24 publications on these topics.
Her career objective is to help students develop an awareness of the skills and attributes of professional scientists, and assist those who are Ph.D. bound to succeed in this aspiration. She is Co-Director of the Minority Opportunities in Research (MORE) programs and Director of the NIH funded Research Initiative for Scientific Enhancement (RISE) program at California State University, Los Angeles. Over 180 MORE fellows from groups traditionally underrepresented in the sciences have obtained their Ph.D. degrees in STEM fields in the past 20 years.
She has mentored over forty students in directed research experiences. While instructing courses in general, atmospheric and physical chemistry, she actively explores innovative pedagogical techniques to develop inquisitive students with refined problem-solving skills that will become leaders in their chosen professions sensitive to the role of chemists and chemistry in the modern world.
About the Seminar:
Elucidating the role of particulate matter on the oxidation capacity of the lower atmosphere
Condenses phase matter suspended in air known as particulate matter (PM) impacts air quality. This paper focuses on explorations of chemical mechanisms that generate aggressive, gaseous oxidants from natural and anthropogenic particulate matter. Topics will include atmospheric
pressure chemical ionization mass spectrometry measurements of gaseous molecular bromine in the high Arctic. These studies link sea-salt particles to surface-level ozone depletion. More recently, we have investigated the formation of singlet molecular oxygen by particle-bound
polycyclic aromatic hydrocarbons, a class of pollutants generated by incomplete combustion processes, such as the consumption of petroleum-based fuels. These studies use laser induced fluorescence techniques to characterize the formation and quenching of singlet molecular oxygen
in solutions containing pyrene, benzoapyrene and oxygenated derivatives of each. Our results show several PAH generate singlet molecular oxygen efficiently with quantum yields near one. Moreover, these compounds quench singlet molecular oxygen at a modest rate, illustrating that
select PAH are not efficient singlet oxygen quenchers. These results suggest that the photodegradation of PAH and oxy-PAH are perpetual sources of singlet molecular oxygen in the lower atmosphere. The environmental implications, including impacts of this chemistry on air quality models, will be discussed.