Margaret Greenslade

ASSOCIATE PROFESSOR
Phone: (603) 862-2475
Office: Chemistry, Parsons Hall Rm S113, Durham, NH 03824
margaret-greenslade

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

Education

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

Research Interests

  • Absorption
  • Aerosol Science
  • Atmospheric Chemistry
  • Atmospheric Physics
  • Atmospheric Sciences
  • Climate Change
  • Marine Atmospheric Chemistry
  • Nano-Materials
  • Physical Chemistry
  • Scattering
  • Spectroscopy

Courses Taught

  • CHEM 684: Physical Chemistry II
  • CHEM 685: Physical Chemistry Laboratory
  • CHEM 696: Independent Study
  • CHEM 699: Thesis
  • CHEM 927: Kinetics and Dynamics
  • INCO 590: Rsrch Exp/Chemistry
  • INCO 790: Adv Rsrch Exp/Chemistry
  • TECH 500: Integrated CEPS Seminar I
  • TECH 501: Integrated CEPS Seminar II

Selected Publications

Morang, J. L., Galpin, T., & Greenslade, M. E. (2018). Effective Refractive Index Values and Single Scattering Albedo Implications for Dry-Generated Clays As Retrieved from Cavity Ring-Down Spectroscopy. Analytical Chemistry, 90(19), 11248-11255. doi:10.1021/acs.analchem.8b01319

Dinneen, S. R., Deravi, L. F., & Greenslade, M. E. (2018). An iterative correction approach used to retrieve the refractive index of squid pigment aerosols. Journal of Optics, 20(3), 034003. doi:10.1088/2040-8986/aaa6ff

Galpin, T., Chartier, R. T., Levergood, N., & Greenslade, M. E. (2017). Refractive index retrievals for polystyrene latex spheres in the spectral range 220–420 nm. Aerosol Science and Technology, 51(10), 1158-1167. doi:10.1080/02786826.2017.1339014

Dinneen, S. R., Greenslade, M. E., & Deravi, L. F. (2017). Optical extinction of size-controlled aerosols generated from squid chromatophore pigments. APL Materials, 5(10), 104802. doi:10.1063/1.5002153

Dinneen, S. R., Osgood, R. M., Greenslade, M. E., & Deravi, L. F. (2017). Color Richness in Cephalopod Chromatophores Originating from High Refractive Index Biomolecules. The Journal of Physical Chemistry Letters, 8(1), 313-317. doi:10.1021/acs.jpclett.6b02398

Greenslade, M. E., Lester, M. I., Radenović, D. Č., van Roij, A. J. A., & Parker, D. H. (2005). (2+1) Resonance-enhanced ionization spectroscopy of a state-selected beam of OH radicals. The Journal of Chemical Physics, 123(7), 074309. doi:10.1063/1.1997132

Marshall, M. D., Davey, J. B., Greenslade, M. E., & Lester, M. I. (2004). Evidence for partial quenching of orbital angular momentum upon complex formation in the infrared spectrum of OH-acetylene. The Journal of Chemical Physics, 121(12), 5845-5851. doi:10.1063/1.1784444

Davey, J. B., Greenslade, M. E., Marshall, M. D., Lester, M. I., & Wheeler, M. D. (2004). Infrared spectrum and stability of a π-type hydrogen-bonded complex between the OH and C2H2 reactants. The Journal of Chemical Physics, 121(7), 3009-3018. doi:10.1063/1.1768933

Radenović, D. Č., van Roij, A. J. A., Chestakov, D. A., Eppink, A. T. J. B., ter Meulen, J. J., Parker, D. H., . . . Lester, M. I. (2003). Photodissociation of the OD radical at 226 and 243 nm. The Journal of Chemical Physics, 119(18), 9341-9343. doi:10.1063/1.1623175

Chartier, R. T., & Greenslade, M. E. (n.d.). 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(4), 709-721. doi:10.5194/amt-5-709-2012

Most Cited Publications