title: Broadly tunable mid-infrared noise-immune cavity-enhanced optical heterodyne molecular spectrometer.
abstract: The sensitive spectroscopic technique noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) has been successfully used in a variety of systems; however, no broadly tunable setup has been developed for the mid-infrared. To this end, we have integrated a difference frequency generation system into a NICE-OHMS setup. Initial optimization and characterization was completed with ro-vibrational spectroscopy of methane. Doppler-broadened frequency-modulated NICE-OHMS spectra were recorded at a sensitivity of 2×10(-7) cm(-1) Hz(-1/2). Sub-Doppler saturation signals (Lamb dips) were also observed using wavelength-modulated NICE-OHMS, achieving a sensitivity of ~6×10(-9) cm(-1) Hz(-1/2).
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Porambo
authors.forename: Brian M
authors.initials: BM
authors.lastname: Siller
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Pearson
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: McCall