Time resolved simultaneous detection of 14NO and 15NO via mid-infrared cavity leak-out spectroscopy.
We present a ring-down absorption spectrometer based on a continuous-wave CO laser in the mid-infrared spectral region near lambda = 5 microm. Using a linear ring-down cavity (length: 0.5 m) with high reflective mirrors (R = 99.988 %), we observed a noise-equivalent absorption coefficient of 3 x 10(-10) cm(-1)Hz(-1/2). This corresponds to a noise-equivalent concentration of 800 parts per trillion (ppt) for (14)NO and 40 ppt for (15)NO in 1 s averaging time. We achieve a time resolution of 1 s which allows time resolved simultaneous detection of the two N isotopes. The delta(15)N value was obtained with a precision of +/-1.2 per thousand in a sample with a NO fraction of 11 ppm. The simultaneous detection enables the use of (15)NO as a tracer molecule for endogenous biomedical processes.
Halmer
Daniel
D
Institut für Lasermedizin, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany.
von Basum
Golo
G
Horstjann
Markus
M
Hering
Peter
P
Mürtz
Manfred
M
D007834:Lasers; D009569:Nitric Oxide / Q000032:analysis* / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000032:analysis*; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods*
D009587:Nitrogen Isotopes; D009569:Nitric Oxide