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

Nitrogen oxides (NOx = NO+NO2) and organic compounds play a central role in ground-level ozone and oxidant formation, stratospheric ozone depletion, and acid deposition.  My primary research objective is to determine quantitatively the kinetics, mechanisms, and products of important homogeneous and heterogeneous atmospheric reactions related to organic compounds and reactive nitrogen species, NOY, where NOY is defined as the sum of NOx and its atmospheric oxidation products.  Understanding atmospheric chemistry of organic compounds and reactive nitrogen species is vital to pollution prevention and control.   

We carried out a number of research projects investigating the kinetics and photochemistry of homogeneous and heterogeneous atmospheric reactions under the support of NSF.  While the earlier work of my group studied the gas phase photochemistry of a wide variety of aldehydes and alkyl nitrates, I have expanded the scope of my research program to address the challenge of lacking sensitive, established technique which can provide quantitative characterization of the heterogeneous photochemical processes at the molecular level.  By exploring the application of a novel variant of cavity ring-down technique, Brewster angle cavity ring-down spectroscopy, my group has successfully determined the room temperature absolute absorption cross sections of HNO3 adsorbed on fused silica surfaces in the 290-365 nm region.  Our study has shown that the surface absorption cross sections of HNO3 are at least two orders of magnitude larger than the cross section values of the HNO3 vapor in the wavelength region studied.  We also determined the quantum yields of the electronically-excited NO2 (NO2*) from the 308 nm photolysis of adsorbed HNO3 on aluminum (Al) surfaces, on ice films, and on fused silica surfaces.  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 the 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.