Investigators and Program Directors
Lei Zhu
Research Scientist, Wadsworth Center
Professor, Environmental Chemistry
Ph.D., Physical Chemistry, Columbia University (1991)
Enrico Fermi Scholar, Chemistry Division, Argonne National Laboratory (1991-1993)
E-mail: zhul@wadsworth.org
Research Interests
Organic compounds and nitrogen oxides (NOx = NO+NO2) are emitted into the atmosphere by natural and anthropogenic sources. They play key roles in a variety of environmental processes such as ground-level ozone formation, stratospheric ozone depletion, acid deposition, and global climate change. My primary research objective is to determine quantitatively the kinetics, mechanisms, and products of homogeneous and heterogeneous atmospheric reactions related to organic compounds and reactive nitrogen species, NOY, where NOY is defined as the sum of NOx and the atmospheric oxidation products of NOx. Understanding atmospheric chemistry of organic compounds and reactive nitrogen species is vital to pollution prevention and control efforts.
We carried out a number of research projects investigating the kinetics and photochemistry of homogeneous and heterogeneous atmospheric reactions related to aldehydes and nitric acid under the support of NSF. My group has determined the wavelength-dependent photolysis quantum yields of aliphatic aldehydes (propionaldehyde, n-butyraldehyde, i-butyraldehyde, n-pentanal, i-pentanal, t-pentanal, n-hexanal, and n-heptanal), aromatic aldehydes (benzaldehyde and 2-nitrobenzaldehyde), and saturated and unsaturated dicarbonyls (glyoxal, methylglyoxal, butenedial, 4-oxo-2-pentenal, and E,E-2,4-hexadienedial) in the actinic UV region by combining laser photolysis with cavity ring-down spectroscopy. Using a novel variant of cavity ring-down technique, my group determined absolute absorption cross sections of adsorbed HNO3 on fused silica surfaces in the 290-330 nm region. My group has also developed a complementary technique to measure UV absorption cross sections of a monolayer of nitric acid adsorbed on aluminum surfaces and on ice films. We have also determined the NO2* quantum yields from the 308 nm nitric acid photolysis in the gas phase, on aluminum surfaces and on ice films. The large near-UV absorption cross sections of HNO3 on surfaces and the large NO2* quantum yield from the 308 nm photolysis of adsorbed HNO3, provide clear evidence that adsorbed HNO3 is not a permanent sink for NOx, as previously assumed.
Contact Information
Phone: (518) 474-6846
Fax: (518) 473-2895
E-mail: zhul@wadsworth.org.