ECOS, University of Massachusetts Boston

Michelle Foster
Adjunct Professor, ECOS

Assistant Professor, Chemistry

Atmospheric Chemistry

Environmental-Physical Chemistry

Chem 312:

Physical Chemistry

Chem 369:

Chemical Structures

michelle.foster@umb.edu
Tel: (617) 287-6096
Fax: (617) 287-6066

Lab Phone: (617) 287-6184

Department of Chemistry
100 Morrissey Blvd.
Boston, MA 02125

 

Curriculum Vitae

Foster Group Website
 
Education
ECOS HR
 
Research Interests
ECOS HR

    Cloud Chemistry

    The role of multiphase reactions on aerosol particles in the troposphere is a very important aspect of the chemistry and cycles of atmospheric trace compounds.  Yet the mechanisms of these reactions are not at all well understood on a molecular level.  This lack of detailed knowledge about these multiphase reactions is a major hindrance when theoretical models of the global atmospheric cycle are used to predict the photochemical oxidant and biogeochemical cycles. 

    My research investigates the mechanisms of heterogeneous tropospheric chemistry.  In this manner, I can follow the last stages of any volatile chemicals life and determine how it affects our atmosphere, especially the role played by dust particles in multiphase atmospheric chemistry. 

    To mimic dust in the laboratory, Magnesium Oxide (MgO) has been chosen as a model oxide system.  The reactions between single crystal MgO and different atmospheric constituents are studied using Fourier transform infrared spectroscopy (FTIR) under a variety of temperature and humidity conditions. 

     
 
Current Research Projects
ECOS HR

Water Thin Films on Magnesium Oxide

 

The presence of thin water films, or adlayers, on dust particles within the atmosphere open up the possibility of chemical reactions occurring within three different regions on the particles.  Reactions can occur on the water surface, or at the water/oxide interface, or within the water layer.  This last option offers an opportunity for solution chemistry to occur within the water thin film.  Thus, the presence of water can greatly influence the reactivity at the surface of the particle and the extent to which dust is able to participate in heterogeneous atmospheric reactions. 

Our studies of water adsorption on the surface of MgO  has shown that the water thin film exhibits hydrogen bonding (H-bonding) between the individual water molecules on the surface even at the lowest coverages detected, and the spectroscopic signal of this thin film of water is almost identical to that of bulk liquid water (same peak energy, but slightly broader).

A plot of the coverage of water on MgO as a function of the water vapor pressure resembles a typical Brunauer, Emmett and

 Teller (BET) adsorption isotherm, indicating that the layer grows in via three-dimensional island formation. This growth mechanism is suggested not only by the isotherm but also by the fact that IR absorption due to the OH stretch of the adsorbed water does not change as a function of coverage. One interesting bit of information discovered during this series of experiments was that water does not wet the MgO surface. At relative humidities as high as 90% the water thin film consists of five layers of water (or five water molecules for every surface atom) as judged using a Beer-Lambert approximation and the cross-section of bulk water absorption as a standard.

 
Teaching
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  • Chemical Structures, Undergraduate Level [Course Syllabus] 
  • Physical Chemistry
  • Analytical Instrumentation
  • Chemical Structures, Graduate Level
  • Chemical Principles  
 
Service Activities
ECOS HR

UMB Home Page     UMass Boston

     Honors Advisory Board

     Faculty Council

 
Current Research Group
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  • Nancy Ward (Graduate, Chemistry) - The study of water thin film formation on metal oxide surfaces: a model for dust interactions in the troposphere.

  • Steve Curtis (Undergraduate, Political Science) - Induced topographical changes on MgO as a function of acid exposure.

  • Eileen Lintz (Undergraduate, Chemistry) - DMMP on MgO, a model for the transport of nerve agents in the tropospheric aerosol.

  • Elena Stoyanova (undergraudate, Biochemistry) - The role of dust particles in the heterogeneous formation of sulfuric acid in the troposphere.

 
 
Selected Publications
ECOS HR

     "An FTIR study of methanol, water and acetic acid on MgO(100) under ambient conditions." Michelle Foster, Devon Passno and Jennifer Rudberg; Submitted to J. Vac. Sci. Technol., October 2003.

    “Thin Film Water on Insulator Surfaces.” George E. Ewing, Michelle Foster, Will Cantrell and Vlad Sadtchenko;  Book Chapter for:  Water in Confined Geometries, eds. V. Buch and J.P. Devlin [Springer-Verlag, Berlin Heidelberg New York, 2003] Chapter 8, pp. 179-212.]

    “An FTIR Study of Water Thin Films on Magnesium Oxide.”  Michelle Foster, Melinda Furse and Devon Passno; Surf. Sci. 502-503, 102-108, 2002.

    “Heterogeneous tropospheric chemistry on mineral dust particles.” Michelle Foster; Prepr. Ext. Absrt. ACS Natl. Meet., Am. Chem. Soc., Div. Environ. Chem. 41, 1228-1232, 2001.

    "Adsorption of water on the NaCl(001) surface.  2. An infrared study at ambient temperatures."  Michelle Foster and George E. Ewing; J. Chem. Phys. 112, 6817, 2000.

    “An infrared spectroscopic study of water thin films on NaCl (100).”  Michelle Foster and George  E. Ewing; Surf. Sci. 427-428, 102-106, 1999.

    “Surface chemistry of alkylsilanes on Si(100) 2×1.”  Michelle Foster; Bill Darlington, Jason   Scharff and Alan Campion; Surf. Sci. 375, 35-44, 1997.

    “On the Mechanism of Chemical Enhancement in Surface-Enhanced Raman Scattering.”  Alan Campion, J. E. Ivanecky, III, C. M. Child and Michelle Foster; J. Am. Chem. Soc. 117, 11807-8, 1995.

    “Adsorption and reactions of ethylsilane on Si(100).”  Michelle Foster, Bill Darlington, Jason  Scharff and Alan Campion; Surf. Sci. 315, L947-L952, 1994.


ECOS HR

© Michelle Foster