Cavity ring-down spectroscopy with an automated control feedback system for investigating nitrate radical surface chemistry reactions

Details

• Alternative Title:
  Rev Sci Instrum
• Personal Author:
  Flemmer, Michael M. ; Ham, Jason E.
• Description:
  Nitrate radical (NO(3)(●)) surface chemistry of indoor environments has not been well studied due to the difficulty in generating and maintaining NO(3)(●) at low concentrations for long term exposures. This article presents the Surface Chemistry Reactant Air Delivery and Experiment System (SCRADES), a novel feedback controlled system developed to deliver nitrate radicals at specified concentrations (50-500 ppt, ±30 ppt) and flow rates (500-2000 ml min(-1)) to a variety of indoor surfaces to initiate reaction chemistry for periods of up to 72 h. The system uses a cavity ring-down spectrometer (CRDS), with a detection limit of 1.7 ppt, to measure the concentration of NO(3)(●) supplied to a 24 l experiment chamber. Nitrate radicals are introduced via thermal decomposition of N(2)O(5) and diluted with clean dry air until the desired concentration is achieved. Additionally, this article addresses details concerning NO(3)(●) loss through the system, consistency of the NO(3)(●) concentration delivered, and stability of the CRDS cavity over long exposure durations (72 h).
• Subjects:
  Automation Feedback Free Radicals Humidity Nitrates Nitrogen Oxides Polytetrafluoroethylene Spectrum Analysis Volatile Organic Compounds
• Source:
  Rev Sci Instrum. 83(8):085103
• Pubmed ID:
  22938328
• Pubmed Central ID:
  PMC4643663
• Document Type:
  Journal Article
• Funding:
  CC999999/Intramural CDC HHSUnited States/
• Volume:
  83
• Issue:
  8
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:8f0a473af50f5848249bf640b52a532125953c82199e3ea957f522928522cca4
• Download URL:
  https://stacks.cdc.gov/view/cdc/36475/cdc_36475_DS1.pdf
• File Type:
  [PDF - 646.67 KB ]