“New Strategies in the Chemical Analysis of Bacterial Biofilms, Photovoltaics
and Other Chemically Complex Nanostructures”
Dr. Luke Hanley, The University of Illinois at Chicago
Chemically complex films, especially those composed of biological and/or semiconductor nanostructures, present unique challenges to traditional methods of analysis. New mass spectrometric (MS) and photoemission strategies, some deploying synchrotron radiation, are applied to their chemical analysis. Laser desorption postionization mass spectrometry (LDPI-MS) can provide chemical information on intact biological and synthetic structures with ~20 mm spatial resolution. LDPI-MS utilizes vacuum ultraviolet radiation for single photon ionization of laser desorbed neutrals. LDPI-MS and matrix assisted laser desorption ionization MS are compared for the analysis of intact bacterial biofilms. Single photon ionization using 7.87 and 10.5 eV radiation from laboratory source is compared with 8.0-12.5 eV tunable synchrotron radiation at the Advanced Light Source in Berkeley. The biofilm analyses demonstrate the ability of higher photon energies to improve sensitivity in LDPI-MS as well as detect new species released from the biofilms by antibiotic treatment. A different problem is posed by photovoltaics based on PbS nanocrystals prepared by cluster beam deposition into a-sexithiophene films. The nanocrystal surface chemistry of these nanocomposite films is determined by Al-Ka and soft-X-ray photoemission, the latter at the Synchrotron Radiation Center in Stoughton, Wis. These results are used in an attempt to correlate nanocrystal surface chemistry with photovoltaic performance.
Luke Hanley is professor and head of chemistry at the University of Illinois at Chicago. He received his PhD from the State University of New York at Stony Brook in 1988 and joined the University of Illinois in 1990. His group’s research is at the interface of analytical chemistry, mass spectrometry, bioengineering and surface science. The group applies advanced instrumental methods to modify and characterize both biological and materials surfaces in several distinct projects. Many of the group’s experimental methods involve photon, ion or cluster interactions with gaseous molecules or solid surfaces that lead to photoionization, photoemission of electrons, sputtering of material from surfaces or deposition of material onto surfaces.