LASER IR (INFRARED) SYSTEM ACCURATELY ANALYZES AUTO EXHAUST GASES

A laser IR (infrared) system has been developed at the General Motors Res. Labs. which can make rapid measurements of all species of interest in the exhaust gas stream (ammonia, hydrocarbons, and the oxides of carbon, sulfur, and nitrogen). This system has been realized through the advent of high-resolution, tunable IR laser diodes. The lifetime of the lead-salt IR laser diodes was extended by the following modifications: plating the "p-side" of the diode with thin layers of gold and indium; and sandwiching another thin layer of platinum between the gold and the indium to prevent indium diffusion. The GM lab now produces lead-salt IR lasers that remain stable for more than a year. To date, sulfuric acid vapor, methane, and carbon monoxide (CO) have been studied with the IR spectrometer equipped with the improved lasers. Controlling factors in sulfate emissions are found to be the fuel sulfur content and the catalyst temperature. Exhaust methane levels are higher (90 to 150 ppm) at idle or during deceleration and much lower (about 10 ppm) during acceleration at high speed. Excursions into lean and rich air/fuel conditions occur even when an engine is set for stoichiometric operation, and CO levels and conversion vary widely during these swings.

• Corporate Authors:

  American Chemical Society

  1155 16th Street, NW
  Washington, DC  United States  20036
• Publication Date: 1980-8-4

Media Info

• Pagination: p. 27
• Serial:
  • Chemical and Engineering News
  • Volume: 58
  • Issue Number: 31
  • Publisher: American Chemical Society

Subject/Index Terms

• TRT Terms: Automobiles; Catalysts; Chemical analysis; Exhaust gases; Infrared radiation; Lasers; Pollutants
• Subject Areas: Safety and Human Factors;

Filing Info

• Accession Number: 00376843
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: HS-030 074
• Files: HSL, USDOT
• Created Date: Jul 30 1983 12:00AM