Ultraviolet photometer for ozone calibration

Conference · Sat Jan 01 04:00:00 EST 1977 · Natl. Bur. Stand. (U.S.), Spec. Publ.; (United States)

OSTI ID:6481366

Bass, A M; Ledford, Jr, A E; Whittaker, J K

In order to provide a facility for photometric ozone measurements, we have designed and constructed a double-beam photometer for ozone concentrations in the range 0.025 to 1.0 ppM. The sample path length of this instrument is approximately 300 cm. The instrument measures changes in ozonized-air sample transmissions of mercury radiation at 253.7 nm where the photoabsorption cross-section of ozone has been well determined. Radiation at wavelengths other than 253.7 nm from the mercury lamp is removed by passing the light through narrow-band interference filters. The light is collimated and passed through a beam splitter which directs approximately equal intensity beams through the two cells. Clean air flows through one cell into the ozone generator and then the ozonized air flows through the second cell. The light beams are recombined on the face of a photomultiplier tube used in the photon counting mode. A rotating chopper allows the two beams to be detected sequentially so that the transmissions of the two cells may be directly observed. Tests indicate that measurements may be made at the 0.05 ppM level with a precision of 10% or better. Ozone calibration data with the 3-meter photometer agreed within 1 and 2% with gas phase titration and uv photometric O/sub 3/ measurements respectively made at the EPA laboratories in Research Triangle Park, North Carolina.

• Research Organization: National Bureau of Standards, Washington, DC
• OSTI ID: 6481366
• Report Number(s): CONF-760985-
• Conference Information: Journal Name: Natl. Bur. Stand. (U.S.), Spec. Publ.; (United States) Journal Volume: 464
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACCURACY
AIR POLLUTION MONITORS
CALIBRATION
COMPARATIVE EVALUATIONS
ELECTROMAGNETIC RADIATION
MEASURING INSTRUMENTS
MEASURING METHODS
MONITORING
OZONE
PHOTOMETERS
PHOTOMETRY
RADIATIONS
STANDARDS
ULTRAVIOLET RADIATION