Monitoring of ethylene by a pulsed quantum cascade laser.
We report on the development and performance of a gas sensor based on a quantum cascade laser operating at a wavelength of approximately 10 microns to measure ethylene (C2H4) concentrations by use of a rotational component of the fundamental nu 7 band. The laser is thermoelectrically cooled and operates in a pulsed mode. The influence of pulse-to-pulse fluctuations is minimized by use of a reference beam and a single detector with time discriminating electronics. Gas absorption is recorded in a 100-m optical path-length astigmatic Herriott cell. With a 10-kHz pulse repetition rate and an 80-s total acquisition time, a noise equivalent sensitivity of 30 parts per billion has been demonstrated. The sensor has been applied to monitor C2H4 in vehicle exhaust as well as in air collected in a high-traffic urban tunnel.
Weidmann
Damien
D
Rice University, 6100 Main Street, Houston, Texas 77251, USA. weidmann@rice.edu
Kosterev
Anatoliy A
AA
Roller
Chad
C
Curl
Robert F
RF
Fraser
Matthew P
MP
Tittel
Frank K
FK