Rate constants of nine C6-C9 alkanes with OH from 230 to 379 K: chemical tracers for [OH].

We report absolute rate-constant measurements for the reactions of nine C(6)-C(9) alkanes with OH in 8-10 torr of nitrogen from 230 to 379 K in the Harvard University High-Pressure Flow System. Hydroxyl concentrations were measured using laser-induced fluorescence, and alkane concentrations were measured using Fourier transform infrared Spectroscopy. Ethane's reactivity was simultaneously measured as a test of experimental performance.

Ozone, trace gas, and particulate matter measurements at a rural site in southwestern New York state: 1995-2005.

A research site for atmospheric chemistry and air pollution measurements was established at Pinnacle State Park in Addison, NY, in 1995. This paper presents an overview of the site characteristics and measurement program, as well as monthly average concentrations for many of the trace gas and aerosol pollutants over the full measurement period. Monthly averaged ozone concentrations range from values as low as 15 parts per billion (ppb) during cold-season months, to values approaching 50 ppb during some spring and summer months.

Synopsis of the temporal variation of particulate matter composition and size.

A synopsis of the detailed temporal variation of the size and number distribution of particulate matter (PM) and its chemical composition on the basis of measurements performed by several regional research consortia funded by the U.S. Environmental Protection Agency (EPA) PM Supersite Program is presented.

A laboratory intercomparison of real-time gaseous ammonia measurement methods.

Six different measurement methods (and seven instruments) for the measurement of gaseous ammonia at low part-per-billion levels were compared simultaneously in a laboratory setting. The instruments were the tunable diode laser (TDL) absorption spectrometer, the wet scrubbing long-path absorption photometer (LOPAP), the wet effusive diffusion denuder (WEDD), the ion mobility spectrometer (IMS), the Nitrolux laser acousto-optical absorption analyzer, and a modified chemiluminescence analyzer. With the exception of the modified chemiluminescence analyzer, the instruments performed well and, understable calibration conditions, generally agreed to within about 25% of the expected calibration value.

Heterogeneous uptake of 8-2 fluorotelomer alcohol on liquid water and 1-octanol droplets.

The heterogeneous uptake of the 8-2 fluorotelomer alcohol, F(CF2)8CH2CH2OH, on liquid water surfaces over the temperature range 256-273 K and on 1-octanol surfaces over the temperature range 264-295 K has been investigated with a droplet train flow reactor. The uptake coefficient on water droplets is zero within the error of the measurement (+/-0.01) and is independent of droplet temperature.

New York State urban and rural measurements of continuous PM2.5 mass by FDMS, TEOM, and BAM.

Field evaluations and comparisons of continuous fine particulate matter (PM2,5) mass measurement technologies at an urban and a rural site in New York state are performed. The continuous measurement technologies include the filter dynamics measurement system (FDMS) tapered element oscillating microbalance (TEOM) monitor, the stand-alone TEOM monitor (without the FDMS), and the beta attenuation monitor (BAM). These continuous measurement methods are also compared with 24-hr integrated filters collected and analyzed under the Federal Reference Method (FRM) protocol.

Real-time measurements of nitrogen oxide emissions from in-use New York City transit buses using a chase vehicle.

New diesel engine technologies and alternative fuel engines are being introduced into fleets of mass transit buses to try to meet stricter emission regulations of nitrogen oxides and particulates: Real-time instruments including an Aerodyne Research tunable infrared laser differential absorption spectrometer (TILDAS) were deployed in a mobile laboratory to assess the impact of the implementation of the new technologies on nitrogen oxide emissions in real world driving conditions. Using a "chase" vehicle sampling strategy, the mobile laboratory followed target vehicles, repeatedly sampling their exhaust. Nitrogen oxides from approximately 170 in-use New York City mass transit buses were sampled during the field campaigns.

Real-time measurements of SO2, H2CO, and CH4 emissions from in-use curbside passenger buses in New York City using a chase vehicle.

The Aerodyne Mobile Laboratory "chased" in-use curbside passenger buses operated by various operators in New York City. With the cooperation of New York State's Metropolitan Transit Authority, the relationships between the emissions of the several gas-phase species and particulate loadings were investigated across several bus technologies, bus types, and fuels (diesel, ultralow sulfur diesel, and compressed natural gas, CNG). The CNG buses followed did not employ an oxidation catalyst.

Long-term field characterization of tapered element oscillating microbalance and modified tapered element oscillating microbalance samplers in urban and rural New York State locations.

Long-term field comparisons of continuous and integrated filter measurements of mass concentrations of particulate matter (PM) with an aerodynamic diameter less than or equal to 2.5 microm (PM2.5) were performed at rural and urban sites in New York State.

Laboratory characterization of modified tapered element oscillating microbalance samplers.

Laboratory tests with generated aerosols were conducted to test the efficacy of two recent design modifications to the well-established tapered element oscillating microbalance (TEOM) continuous particulate matter (PM) mass monitor. The two systems tested were the sample equilibration system-equipped TEOM monitor operating at 30 degrees C, which uses a Nafion dryer as part of the sample inlet, and the differential TEOM monitor, which adds a switched electrostatic precipitator and uses a self-referencing algorithm to determine "true PM mass." Test aerosols included ammonium sulfate, ammonium nitrate, sodium chloride, copper (II) sulfate, and mixed aerosols.

Semicontinuous PM2.5 sulfate and nitrate measurements at an urban and a rural location in New York: PMTACS-NY summer 2001 and 2002 campaigns.

Several collocated semicontinuous instruments measuring particulate matter with particle sizes < or =2.5 microm (PM2.5) sulfate (SO4(2-)) and nitrate (NO3-) were intercompared during two intensive field campaigns as part of the PM2.

Gas-phase ozonolysis of alkenes: formation of OH from anti carbonyl oxides.

Gas-phase ozone-alkene reactions are known to produce the hydroxyl radical (OH) in high yields. Most mechanistic studies to date have focused on the role of syn carbonyl oxides; however, OH production from ethene ozonolysis indicates a second, poorly understood OH-forming channel, which may contribute to OH production in the ozonolysis of substituted alkenes as well. Using laser-induced fluorescence, we have measured OH and OD yields from the ozonolysis of two partially deuterated alkenes, cis- and trans-3-hexene-3,4-d2.

Mechanism of HO Formation in the Gas-Phase Ozone-Alkene Reaction. 1. Direct, Pressure-Dependent Measurements of Prompt OH Yields.

The gas-phase reaction of ozone with alkenes is known to be a dark source of HO radicals (such as OH, H, and R) in the troposphere, though the reaction mechanism is currently under debate. It is understood that a key intermediate in the reaction is the carbonyl oxide, which is formed with an excess of vibrational energy. The branching ratios of the ozone-alkene reaction products (and thus HO yields) depend critically on the fate of this intermediate:  it may undergo unimolecular reaction (forming either OH or dioxirane) or be collisionally stabilized by the bath gas.