Trace moisture detection using continuous-wave cavity ring-down spectroscopy.

Mid-infrared continuous wave cavity ring down spectroscopy of molecular ions using an optical parametric oscillator

A sensitive infrared detection scheme is presented in which continuous wave cavity ring down spectroscopy is used to record rovibrational spectra of molecular ions in direct absorption through supersonically expanding planar plasma. A cw optical parametric oscillator is used as a light source and combines a broad spectral coverage (2100–3600 cm ) and narrow bandwidth (7 kHz) with a high output ...

Evanescent Wave Cavity Ring-down Spectroscopy: a Future Technology for Process Sensing

Evanescent wave cavity ring-down spectroscopy (EW-CRDS) is described. The total internal reflection (TIR)-ring and monolithic folded cavity designs are briefly discussed. The performance of EW-CRDS for trace water vapor detection is evaluated by accounting for surface chemical and physical properties as well as intrinsic resonator properties. INTRODUCTION Cavity ring-down spectroscopy (CRDS) us...

Sensitive trace gas detection with cavity enhanced absorption spectroscopy using a continuous wave external-cavity quantum cascade laser

Moving beyond traditional UV-visible absorption detection: cavity ring-down spectroscopy for HPLC.

We describe the use of liquid-phase continuous-wave cavity ring-down spectroscopy for the detection of an HPLC separation. This technique builds on earlier work by Snyder and Zare using pulsed laser sources and improves upon commercially available UV-visible detectors by a factor of up to 50. The system employs a compact doubled-diode single-mode continuous-wave laser operating at 488 nm and a ...

Quantitative Moisture Measurement with a Cavity Ring-down Spectrometer using Telecom Diode Lasers

Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy (CRDS). By using different absorption lines of H2O in the 1.56 and 1.36 μm regions, we are able to determine the relative concentration (mole fraction) of water vapor from a few percent down to the 1...