Positions

Research Areas research areas

Overview

  • RESEARCH OVERVIEW: In the Greenslade group, we have been focused on studying atmospheric aerosols and the chemicals that compose these. Aerosols are ubiquitous in the atmosphere and play intriguing roles in physical and chemical processes impacting fields such as atmospheric sciences, climate, combustion, medicine, and health. Aerosols are fine, solid or liquid particles suspended in a gaseous medium. The bulk of aerosols are 10s to 100s of nanometers in diameter and are composed of many molecules thus can have complicated chemical compositions. We investigate aerosol properties using physical chemistry, specifically spectroscopic methods and relate the results to broader questions, especially regarding climate change.

    Complex aerosols are of special interest. Whether uniquely shaped or of mixed composition, we are interested in understanding their optical and morphological properties and how these change as a function of environmental influence.

    One of the main techniques we use is cavity ring-down (CRD) spectroscopy at 532 nm using the frequency doubled Nd:YAG output. This green wavelength is near the center of the solar spectrum. Because the technique relies on the time decay of the light in the cavity instead of intensity changes, random fluctuations have limited impact and the instrument is especially sensitive to small optical changes, even extinction from just one aerosol particle! One other advantage of our instrument is that it also allows for the interrogation of aerosols before and after an environmental change.

    Our other main spectroscopic tool is the AE-DOAS instrument. This is another custom instrument which was built for us by Cerex Monitoring Solutions. It is based on a standard UV/Vis spectrometer but it uses a multipass gas cell with an adjustable path length of up to nearly 20 m for in situ determination of aerosol extinction. Having the best detection limit from 235-700 nm with a resolution of 0.5 nm, it has unique broad band capabilities to capture the wavelength dependence of aerosol optical properties.

    CURRENT GROUP MEMBERS:
    Jillian Morang, Vahid Hosseinpour Hashemi, Jackson Kaspari;

    GROUP ALUMNI:

    Postdoctoral
    Elizabeth Frinak Mentis;

    Graduate
    Alexis Attwood,,Ryan Chartier, Douglas Collins, James Hendrickx, Tyler Galpin, Sean Dinneen (co-advised with Prof. Deravi);

    Undergraduate
    Justin Pleva, Jennifer Pollock, Olivia Segit-Rix, Jasmine Humphries, Carleen Dingman, Nicholas Levergood, Zachary Rice, Adam Knedeisen, Meaghan Elrick, Matthew Reuter, Christopher Redus, Anthony Jennings, Cynthia Gerber, Brent Lawson, Jackson Kaspari, Alexandra Singh
  • Publications

    Academic Article

    Year Title
    2018 Effective Refractive Index Values and Single Scattering Albedo Implications for Dry-Generated Clays As Retrieved from Cavity Ring-Down Spectroscopy.Analytical Chemistry Industrial and Engineering Chemistry Analytical Edition.  90:11248-11255. 2018
    2018 An iterative correction approach used to retrieve the refractive index of squid pigment aerosolsJournal of Optics A: Pure and Applied Optics Journal of Optics Pure and Applied Optics Journal of Optics.  20:034003-034003. 2018
    2017 Optical extinction of size-controlled aerosols generated from squid chromatophore pigmentsAPL Materials.  5:104802-104802. 2017
    2017 Color Richness in Cephalopod Chromatophores Originating from High Refractive Index Biomolecules.Journal of Physical Chemistry Letters.  8:313-317. 2017
    2017 Refractive index retrievals for polystyrene latex spheres in the spectral range 220-420 nmAerosol Science and Technology.  51:1158-1167. 2017
    2015 Spectral aerosol extinction (SpEx): a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength rangeAtmospheric Measurement Techniques.  8:4755-4771. 2015
    2012 Deliquescence behavior of internally mixed clay and salt aerosols by optical extinction measurements.Journal of Physical Chemistry A.  116:4518-4527. 2012
    2012 Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass Aerosol Extinction Differential Optical Absorption Spectrometer (AE-DOAS)Atmospheric Measurement Techniques.  5:709-721. 2012
    2011 Optical Properties and Associated Hygroscopicity of Clay AerosolsAerosol Science and Technology.  45:1350-1359. 2011
    2005 (2+1) resonance-enhanced ionization spectroscopy of a state-selected beam of OH radicals.Journal of Chemical Physics.  123:074309. 2005
    2005 Fluorescence-dip infrared spectroscopy and predissociation dynamics of OH A 2Sigma+ (v = 4) radicals.Journal of Chemical Physics.  122:244313. 2005
    2004 Evidence for partial quenching of orbital angular momentum upon complex formation in the infrared spectrum of OH-acetylene.Journal of Chemical Physics.  121:5845-5851. 2004
    2004 Infrared spectrum and stability of a pi-type hydrogen-bonded complex between the OH and C2H2 reactants.Journal of Chemical Physics.  121:3009-3018. 2004
    2003 Photodissociation of the OD radical at 226 and 243 nmJournal of Chemical Physics.  119:9341-9343. 2003
    2002 Electronic spectroscopy of the OH-CO reactant complexChemical Physics Letters.  354:203-209. 2002

    Conference Proceeding

    Year Title
    2016 Field assessment of optical transparency in the low-level marine boundary layer: preliminary data from coastal New England sitesProceedings of SPIE - The International Society for Optical Engineering. 2016
    2016 Optical properties of salt aerosols with and without inclusions as a function of relative humidityProceedings of SPIE - The International Society for Optical Engineering. 2016
    2014 Enhancement in optical properties of dust upon mixing with dicarboxylic acidsACS National Meeting Book of Abstracts. 2014
    2010 Optical properties and associated hygroscopicity of clay aerosols and their mixtures with ammonium sulfateACS National Meeting Book of Abstracts. 2010
    2010 Wavelength and humidity dependent aerosol extinctionACS National Meeting Book of Abstracts. 2010
    2004 Investigation of the hydrogen bonded OH-acetylene reactant complex by OH overtone and asymmetric CH stretch excitation.ACS National Meeting Book of Abstracts. U276-U276. 2004

    Teaching Activities

  • Integrated CEPS Seminar I Taught course 2018
  • Physical Chemistry Laboratory Taught course 2018
  • Physical Chemistry Laboratory Taught course 2018
  • Physical Chemistry Laboratory Taught course 2018
  • Physical Chemistry Laboratory Taught course 2018
  • Physical Chemistry Laboratory Taught course 2018
  • Integrated CEPS Seminar II Taught course 2018
  • Physical Chemistry II Taught course 2018
  • Thesis Taught course 2018
  • Thesis Taught course 2017
  • Thesis Taught course 2017
  • Adv Rsrch Exp/Chemistry Taught course 2016
  • Integrated CEPS Seminar I Taught course 2016
  • Physical Chemistry Laboratory Taught course 2016
  • Rsrch Exp/Chemistry Taught course 2016
  • Thesis Taught course 2016
  • Kinetics and Dynamics Taught course 2016
  • Physical Chemistry II Taught course 2016
  • Thesis Taught course 2016
  • Adv Rsrch Exp/Chemistry Taught course 2015
  • Rsrch Exp/Chemistry Taught course 2015
  • Thesis Taught course 2015
  • Independent Study Taught course 2015
  • Physical Chemistry II Taught course 2015
  • Rsrch Exp/Chemistry Taught course 2015
  • Independent Study Taught course 2014
  • Physical Chemistry Laboratory Taught course 2014
  • Physical Chemistry Laboratory Taught course 2014
  • Physical Chemistry Laboratory Taught course 2014
  • Physical Chemistry Laboratory Taught course 2014
  • Physical Chemistry Laboratory Taught course 2014
  • Sem/Analytical-Physical Taught course 2014
  • General Chemistry II Taught course 2014
  • Thesis Taught course 2014
  • Education And Training

  • B.A. Chemistry, Bryn Mawr College
  • Ph.D. Physical Chemistry, University of Pennsylvania
  • Full Name

  • Margaret Greenslade