Article

Ultrasensitive detection of nitric oxide at 5.33 m by using external cavity quantum cascade laser-based Faraday rotation spectroscopy

Rice Quantum Institute, Rice University, 6100 Main Street, Houston, TX 77005, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 08/2009; 106(31):12587-92. DOI: 10.1073/pnas.0906291106
Source: PubMed

ABSTRACT A transportable prototype Faraday rotation spectroscopic system based on a tunable external cavity quantum cascade laser has been developed for ultrasensitive detection of nitric oxide (NO). A broadly tunable laser source allows targeting the optimum Q(3/2)(3/2) molecular transition at 1875.81 cm(-1) of the NO fundamental band. For an active optical path of 44 cm and 1-s lock-in time constant minimum NO detection limits (1sigma) of 4.3 parts per billion by volume (ppbv) and 0.38 ppbv are obtained by using a thermoelectrically cooled mercury-cadmium-telluride photodetector and liquid nitrogen-cooled indium-antimonide photodetector, respectively. Laboratory performance evaluation and results of continuous, unattended monitoring of atmospheric NO concentration levels are reported.

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Available from: Frank K Tittel, Aug 29, 2015
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    • "Photoacoustic spectroscopy (PAS) is one of the most effective approaches to detect trace gas because of its sensitive and selective characteristics [13] [14] [15] [16]. Compared with other optical spectroscopic technique [17] [18] [19] [20], PAS has two advantages: one is the wavelength-independent relationship between the PAS spectrophone and excitation light source. It means that the same PAS spectrophone can be employed to detect a variety of trace gases with different absorption spectra, regardless of the excitation light source wavelengths. "
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    • "Dispersion lineshape functions are the basis for spectroscopic techniques that measure the interference between two (or several) light fields. Examples of such techniques are Faraday modulation/rotation spectroscopy (FAMOS/FRS) [1] [2] [3] [4], frequency modulation spectroscopy (FMS), and thereby noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) [5] [6] [7], and chirped laser dispersion spectroscopy (CLaDS) [8] [9] [10] [11]. They are often used to assess the concentration of molecular species in gas phase, most frequently in trace concentrations. "
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    • "However, despite offering sufficient quality for breath analysis, no clinical study on breath analysis has been performed so far with such sensors. Till recently, FRS methods have been applied successfully for on-line NO detection with QCLs replacing CO lasers [46] [47] [48] [49]. FRS sensors have been offering sub-ppb detection limit with sub-second response time and were successfully implemented in measuring biogenic nitric oxide concentration [50]. "
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