title: Trace gas detection by laser intracavity photothermal spectroscopy.
abstract: A novel laser intracavity photothermal detector is described. In this scheme, sample absorption of the pump laser power takes place within the cavity of a probe He-Ne laser causing modulation in the gain and in turn the output power. Comparison of this intracavity detector with two other photothermal techniques, namely, phase fluctuation optical heterodyne spectroscopy and thermal beam deflection, is made in terms of practicality and sensitivity. For in situ measurements, sensitivity of 0.5 x 10(-7) cm(-1) for a probe length of 3 cm has been achieved.
authors.affiliation: Brookhaven National Laboratory, Department of Applied Science, Environmental Chemistry Division, Upton, New York 11973, USA.
authors.forename: K H
authors.initials: KH
authors.lastname: Fung
authors.forename: H B
authors.initials: HB
authors.lastname: Lin