dc.creator Lin, Horn-Bond en_US dc.creator Campillo, Anthony J. en_US dc.date.accessioned 2006-06-15T14:29:07Z dc.date.available 2006-06-15T14:29:07Z dc.date.issued 1980 en_US dc.identifier 1980-FB-16 en_US dc.identifier.uri http://hdl.handle.net/1811/11145 dc.description 1. C.C. Davis, Appl .Phys. Lett. 36, 515--519 (1980). $^{\dag}$ This work was performed under the auspices of the United States Department of Energy under Contract No. DE-AC02-76CH00016. en_US dc.description Author Institution: en_US dc.description.abstract We describe operation of a cw laser heterodyne interferometer of the type proposed by Davis (1). This device should be useful for probing weakly absorbing molecular species. In preliminary results we have obtained sensitivities of $10^{-8}$ $cm^{-1}$, competitive with photoacoustic spectroscopy (PAS). As a demonstration of its capabilities we have performed Stark spectroscopy of the $\nu_{2}$ band of $NH_{2}D$ and $NH_{3}$. This technique, like PAS, is calorimetric. A grating tuned $CO_{2}$ laser is operated at a wavelength absorbed by the species of interest and as the sample gas is heated via collisional quenching, a small change in density and refractive index is induced. The latter is monitored by placing the sample in an ultrasensitive He-Ne laser heterodyne interferometer capable of detecting refractive index changes as small as $10^{-11}$. When used in Stark studies, this approach has greater sensitivity than that obtained using long path differential absorption and is free from the electric field induced background signal that is encountered when empoying PAS. en_US dc.format.extent 122397 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title AN ULTRASENSITIVE LASER HETERODYNE INTERFEROMETER FOR MOLECULAR ABSORPTION $SPECTROSCOPY^\dag$ en_US dc.type article en_US
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