Jesse Kroll’s laboratory is located in the Parsons Laboratory for Environmental Science and Engineering. A major feature of the laboratory is an environmental chamber for the study of gas-phase chemistry and secondary organic aerosol formation. The chamber consists of a temperature-controlled room (10C-40C), containing fluorescent blacklights (centered at 350 nm, 1.8 kW total) and an inner chamber (7.5 m3) in which the reactions are run. A number of analytical instruments are available for the measurement of the chemistry within the chamber, including a high-resolution time-of-flight aerosol mass spectrometer, another high-resolution mass spectrometer for the measurement of semivolatile and intermediate-volatility organics; a filter sampler for offline chemical analysis; a scanning mobility particle sizer; a GC-FID; an NO/NOx chemiluminescence monitor; and an O3 monitor. Several other smaller reactors (a chamber and two flow tubes) are currently under construction.
Daniel Cziczo’s “Aerosol and Cloud Lab” is located in the Department of Earth, Atmospheric and Planetary Sciences’ Green Building and contains a set of instrumentation for the production and investigation of small particles and how they interact with water vapor to form liquids and ices. Aerosol particles from nanometer to super-micrometer diameter can be produced from aqueous solution and via dry dispersion. Particles can be produced in a poly-disperse population or separated to mono-disperse groupings using differential mobility analysis (Brechtel Manufacturing, Inc.). Particle counting is accomplished with condensation particle counters and size resolution with optical particle counters (TSI, Inc.). A wide range of particles can be produced from a variety of mineral dusts, elemental carbon, and metals readily available in the lab or ground from bulk samples. Aqueous solutions of salts, organics and sea water can be atomized from laboratory stock.
Ice nucleation is currently accomplished using two chambers. The first is a custom designed flow tube used for the contact nucleation of particulate matter and droplets and includes an FTIR spectrometer for phase information (Bruker Optics) coupled with a low temperature (-90° C) circulating bath (Lauda-Brinkman). The second is commercially available and based on our design. This chamber uses compact refrigeration technology to form ice clouds from 0 to -65° C (Droplet Measurement Technologies SPIN-100). Inertial separation techniques, termed counterflow virtual impaction (CVI), are used to separate droplets and ice crystals from unactivated aerosol for subsequent analysis of either subset.
Aerosol chemical composition is accomplished both at MIT’s Electron Microscope Facility and with our Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. PALMS utilizes a 193 nm laser to ablate and ionize components on a particle by particle basis and thereby produce a time of flight mass spectrum. It is noteworthy that all techniques present in the Aerosol and Cloud Lab have been developed to be field deployable and can thus be transported to other laboratories.
Ronald Prinn’s laboratory is located in the Department of Earth, Atmospheric and Planetary Sciences’ Green Building. The laboratory focuses on high-frequency on-site measurements of the major atmospheric gases involved in climate change and ozone-layer depletion. The laboratory assembles and deploys in the field instruments for the AGAGE global network, for individual doctoral thesis work (e.g., recently Drs. Kat Potter, Laura Meredith, and Anita Ganesan) and for the recent development of high-frequency measurements of isotopic composition of gases (see below).
Shuhei Ono and Ronald Prinn, in cooperation with Aerodyne Research Inc. have developed an instrument for on-site monitoring of tropospheric nitrous oxide isotopomer ratios (15N14N16O/14N15N16O/14N14N16O). The instrument utilizes Aerodyne Research’s quantum cascade mid-infrared laser spectroscopy combined with liquid-nitrogen free preconcentration unit used for AGAGE network. The instrument measures isotopomer ratios at every 20 min at ca. 0.2 ‰ precision (2s) fully autonomously. It is currently deployed at the Green Building to analyze air sampled from the roof of the building. The instrument will be deployed at one of the AGAGE stations in early 2013. This will be used to better quantify the source and sink strengths of toropospheric nitrous oxide.
Shuhei Ono’s group uses isotope ratio mass-spectrometer (MAT 253) for high precision measurements of four sulfur isotope abundances (32S, 33S, 34S, 36S). We calibrate isotope fractionations for some key sulfur photochemical reactions. The lab also hosts four gas chromatography instruments for analyses of various trace gases (e.g., H2, CO, CH4, N2O, CO2)