Abstract. We demonstrate a compact, open-path, quantum cascade-laser-based atmospheric ammonia sensor operating at 9.06 μm for high-sensitivity, high temporal resolution, ground-based measurements. Atmospheric (NH3) is gas-phase precursor to fine particulate matter, with implications air quality and climate change. Currently, NH3 sensing challenges have led lack of widespread in situ Our open-path configuration minimizes sampling artifacts associated surface adsorption onto inlet tubing...

Ammonia (NH3) is a key precursor species to atmospheric fine particulate matter with strong implications for regional air quality and global climate change. NH3 from vehicles accounts significant fraction of total emissions in urban areas. A mobile platform developed measure NH3, CO, CO2 the top passenger car. The conducted 87 h on-road measurements, covering 4500 km New Jersey California. average emission factor (EF) CA 0.49 ± 0.06 g per kg fuel agrees previous studies (0.3–0.8 g/kg). mean...

A compact and portable open-path sensor for simultaneous detection of atmospheric N(2)O CO has been developed with a 4.5 μm quantum cascade laser (QCL). An in-line acetylene (C(2)H(2)) gas reference cell allows continuous monitoring the drift calibration in rapidly changing field environments thereby at high precision stability. Wavelength modulation spectroscopy (WMS) is used to detect simultaneously both second fourth harmonic absorption spectra an optimized dual amplitude scheme....

We report the characteristics of current induced frequency modulation (FM) for two continuous-wave quantum cascade lasers (QCLs) at 9.06 μm. Both tuning rate and phase shift between intensity FM are measured different frequencies from 10 Hz to 200 kHz. The QCLs depends on both amplitude. tested QCL has been used detect ambient water vapor with wavelength spectroscopy validation a numerical model.

Abstract. We demonstrate a compact, open-path, quantum cascade laser-based atmospheric ammonia sensor operating at 9.06 μm for high sensitivity, temporal resolution, ground-based measurements. Atmospheric (NH3) is gas-phase precursor to fine particulate matter, with implications air quality and climate change. Currently, NH3 sensing challenges have led lack of widespread in-situ Our open-path configuration avoids sampling artifacts associated surface adsorption onto inlet tubing reduced...

This paper investigates the impact of quantum cascade laser’s frequency modulation response on its tuning rate and tunability. We show a significant disparity in laser rates tunability between single dual-frequency schemes frequently used typical direct absorption wavelength spectroscopy (WMS) techniques. that DC-characterized can be reduced significantly under specific set frequencies injection current. characterize these effects by simultaneous measurements higher harmonic WMS methane...

Several environmental trace gas species and toxic chemicals or warfare simulants have fingerprint spectral signatures in the mid-infrared region of spectrum. For instance, methane, nitrous oxide, water vapor are critical greenhouse gases relevant for sensing. In contrast, Sarin is one most lethal agents that a highly synthetic chemical organophosphorus compound, which interest defense security sensing applications. Due to complex structure significant absorption collision cross-section,...

A novel compact quantum cascade laser (QCL) based open-path gas sensor has been developed for simultaneous detection of atmospheric N2O and CO. The achieves a sensitivity 0.26 ppbv 0.24 CO with 1 Hz sample rate.

Shannon's information theory is applied to Wavelength Modulation Spectroscopy (WMS) providing quantitative figures of merit such as the measurement precision and a prediction optimal detection harmonic order be used. The amount information, in bits, that can extracted any WMS calculated. experimental results we have obtained experiments congested spectra with overlapping lines highly disparate absorption cross-sections. A key result complexity signal structure play much more important role...

An open-path quantum cascade laser atmospheric ammonia sensor is demonstrated in a range of field environments. The low power, compact with 500pptv detection limit 1s addresses the unique challenges for robust in-situ sensing.

techniques to measure changes of the translational diffusion times and rotational two nanoprobes, Alexa488 FITC-Ficoll, dispersed in aqueous Ficoll solutions at room temperature. Analysis data indicated that lifetimes nanoprobes appeared be unaltered by solutions. In contrast, FCS functions each nanoprobe, which demonstrated slowing down due Ficoll, were adequately fitted with expression a freely diffusing nanoparticle. Similarly, FA both was slowed down. The could not accounted for,...

Wavelength Modulation Spectroscopy (WMS) has been extensively used as a tool for sensitive detection through precise measurements of the absorption lineshape function gaseous species. In this paper pathlength saturation in wavelength modulation spectroscopy is studied. New effects are found when one takes advantage demodulation at higher harmonics frequency. We show here that much more probe these effects. particular, synchronous performed frequency, even very small become clearly visible....

We show sensitive detection of methane using laser based spectroscopy systems. compare two regimes in 1654 nm and 7843 wavelength range, the near infrared mid-infrared region spectrum.

We show sensitive detection of methane, nitrous oxide and water-vapor using quantum cascade laser based spectroscopy systems. The technique is on direct absorption wavelength modulation to resolve enhance sensitivity.