Effective utilization of quantum-cascade distributed-feedback lasers in absorption spectroscopy.
A variable duty cycle quasi-cw frequency scanning technique was applied to reduce thermal effects resulting from the high heat dissipation of type I quantum-cascade lasers. This technique was combined with a 100-m path-length multipass cell and a zero-air background-subtraction technique to enhance detection sensitivity to a parts-in-10(9) (ppb) concentration level for spectroscopic trace-gas detection of CH4, N2O, H2O, and C2H5OH in ambient air at 7.9 micrometers. A new technique for analysis of dense high resolution absorption spectra was applied to detection of ethanol in ambient air, yielding a 125-ppb detection limit.
Kosterev
A A
AA
Rice Quantum Institute, Rice University, Houston, Texas 77251-1892, USA. akoster@rice.edu
Curl
R F
RF
Tittel
F K
FK
Gmachl
C
C
Capasso
F
F
Sivco
D L
DL
Baillargeon
J N
JN
Hutchinson
A L
AL
Cho
A Y
AY
D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation*; D004867:Equipment Design; D000431:Ethanol / Q000032:analysis; D005069:Evaluation Studies as Topic; D005740:Gases / Q000032:analysis*; D007834:Lasers; D016014:Linear Models; D008697:Methane / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D013054:Spectrophotometry, Atomic / Q000295:instrumentation*; D013696:Temperature; D014867:Water / Q000032:analysis
D005740:Gases; D014867:Water; D000431:Ethanol; D009609:Nitrous Oxide; D008697:Methane