title: Doppler-free nonlinear absorption in ethylene by use of continuous-wave cavity ringdown spectroscopy.
abstract: We report what we believe to be the first systematic study of Doppler-free, nonlinear absorption by use of cavity ringdown spectroscopy. We have developed a variant of cavity ringdown spectroscopy for the mid-infrared region between 9 and 11 microm, exploiting the intracavity power buildup that is possible with continuous-wave lasers. The infrared source consists of a continuous-wave CO2 laser with 1-mW tunable infrared sidebands that couple into a high-finesse stable resonator. We tune the sideband frequencies to observe a saturated, Doppler-free Lamb dip in the nu7, 11(1,10) <-- 11(2,10) rovibrational transition of ethylene (C2H4). Power studies of the Lamb dip are presented to examine the intracavity effects of saturation on the Lamb-dip linewidth, the peak depth, and the broadband absorption.
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA. christine.bucher@mpq.mpg.de
authors.forename: C R
authors.initials: CR
authors.lastname: Bucher
authors.forename: K K
authors.initials: KK
authors.lastname: Lehmann
authors.forename: D F
authors.initials: DF
authors.lastname: Plusquellic
authors.forename: G T
authors.initials: GT
authors.lastname: Fraser