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Investigators and Program Directors

Lei Zhu

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)


Research Interests

Solar radiation plays an important role in photochemical reactions of the atmosphere. In the presence of sunlight, nitrogen oxides (NOx = NO+NO2) and organic compounds emitted by automobiles can react under hot conditions to form ground-level ozone and photochemical smog. Thus, human activity is altering the chemical composition of the atmosphere and affecting the balance between the incoming solar radiation and the outgoing thermal energy. To holistically understand the earth system, we need to know what affects the energy balance of the atmosphere and how chemical reactions impact chemical composition of the earth system.

My group has carried out a number of research projects to address important issues influencing atmospheric radiative balance and chemistry with National Science Foundation support :

  • Recently demonstrated water vapor to exhibit near UV absorption in the 290-350 nm region. By coupling experimentally-determined water vapor cross section data with modeling of the solar flux at the ground using radiative transfer model, my group and a collaborator have shown that water vapor absorption in the 290-350 nm region can cause significant difference in solar flux at the ground (up to 22% for standard US atmosphere).
  • By exploring the application of a novel variant of cavity ring-down technique, Brewster angle cavity ring-down spectroscopy, my group recently determined absorption cross sections of surface-adsorbed H2O in the 295-370 nm region and the heterogeneous nucleation of H2O on surfaces. Surface water cross section values are found to be 4 orders of magnitude larger than gas or liquid water cross section values.
  • Measured absorption cross sections of HNO3 adsorbed on fused silica surfaces in the 290-365 nm region. Our study has shown that surface absorption cross sections of HNO3 are at least two orders of magnitude larger than those in the gas phase. We also obtained the quantum yields of the electronically-excited NO2 (NO2*) from 308 nm photolysis of HNO3 in the gas phase, on aluminum (Al), ice, and fused silica surfaces. We provide clear evidence that adsorbed HNO3 is not a permanent sink for NOx, as previously assumed.
  • Earlier works investigated gas phase photochemical reactions involving vinoxy/O2, alkyl nitrates, and a wide variety of aldehydes - all of which are oxidation products of atmospheric organic compounds. Results of our studies have filled in key missing values in atmospheric chemistry models. My group also pioneered the application of cavity ring-down spectroscopy in studying atmospheric photochemistry.
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Contact Information

Phone: (518) 474-6846
Fax: (518) 473-2895