ABSTRACT
Cavity ringdown spectroscopy (CRDS) is a laser absorption spectral technique. Although several different forms of CRDS have been evolved from the original concept, the common features remain the same and exist in each form of CRDS: high detection sensitivity, high selectivity, absolute number density measurements, near real-time response, and immune-to-light source fluctuations. Over the past 10 years, CRDS has been extended from original spectroscopic studies to its applications in a wide variety of fields, such as environment, energy, medicine, materials, and sensing and diagnostics. One emerging application of CRDS is coupling CRDS with a plasma source, namely, plasma-cavity ringdown spectroscopy (P-CRDS), for plasma diagnostics and absolute number density measurements of plasma species in time and in space. Along with latest advancements of nonthermal, low-temperature plasmas and their new applications in medicine, combustion, and material processing, P-CRDS, as a versatile diagnostic tool, begins to play an increasingly important role in the aforementioned
8.1 Introduction ......................................................................................207 8.2 Concept of CRDS ..............................................................................208
