15min:

D. FORTHOMME, C. MCRAVEN, G. E. HALL, T. J. SEARS, Chemistry Department, Brookhaven National Laboratory, Bldg. 555A, P.O. Box 5000, Upton, NY 11973, USA.

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A spectrometer for measuring sub-Doppler saturation spectra in a discharge flow cell has been built and tested on the (1-0) band of the B³ _g-A^{3 +}_u electronic transition of ¹⁴N₂ near 11250 cm^-1. A cw Ti:sapphire laser is stabilized relative to a single frequency HeNe laser and offset scanned with a RF synthesizer. An amplitude-modulated bleach beam is counter-propagated with a phase-modulated probe beam through the discharge cell. Absorption and dispersion phase signals are demodulated in a probe beam receiver, then demodulated at the lower bleach modulation frequency and finally averaged with lock-in detection at the audio frequency of the AC-discharge. Isolated hyperfine lines are observed with a FWHM of about 7 MHz and the splittings can be recorded with a precision of a few hundred kHz. Comparisons will be made with more extensive prior work by Giesen et al.