Cavity ringdown spectroscopy using mid-infrared quantum-cascade lasers.
Cavity ringdown spectra of ammonia at 10 parts in 10(9) by volume (ppbv) and higher concentrations were recorded by use of a 16-mW continuous-wave quantum-casacde distributed-feedback laser at 8.5 mum whose wavelength was continuously temperature tuned over 15 nm. A sensitivity (noise-equivalent absorbance) of 3.4x10(-9) cm(-1) Hz(-1/2) was achieved for ammonia in nitrogen at standard temperature and pressure, which corresponds to a detection limit of 0.25 ppbv.
Paldus
B A
BA
Harb
C C
CC
Spence
T G
TG
Zare
R N
RN
Gmachl
C
C
Capasso
F
F
Sivco
D L
DL
Baillargeon
J N
JN
Hutchinson
A L
AL
Cho
A Y
AY