15min:

RICHARD MAWHORTER, BENJAMIN MURPHEY, ALEXANDER BAUM, Department of Physics and Astronomy, Pomona College, Claremont, CA 91711; TREVOR J. SEARS, Chemistry Department Brookhaven National Laboratory, Upton, NY 11973 and Stony Brook University, Stony Brook, NY 11794; T. ZH. YANG, P. M. RUPASINGHE, C. P. MCRAVEN, N. E. SHAFER-RAY, Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK; LUKAS D. ALPHEI AND JENS-UWE. GRABOW, Gottfreid-Wilhelm-Liebniz-Universität, Institut für Physikalische Chemie & Elektrochemie, D-30167 Hannover, Germany.

We have measured rotational transitions in the ground, X₁~² _1/2, electronic state of naturally occuring isotopomers of PbF in a supersonic free jet Fourier transform microwave spectrometer. The data for ²⁰⁷Pb¹⁹F is particularly interesting because it is a candidate for a future experimental e-EDM measurement. To fit the data for this species to the measurement precision, the nuclear spin-spin dipolar interaction and a second term that can be equivalently viewed as a centrifugal distortion correction to the familiar Frosch and Foley hyperfine coupling terms, or an - dependent correction to the nuclear spin-rotational coupling are required, in addition to the standard terms. To characterize the higher X₂~² _3/2 component of the ground state of PbF, we are attempting a direct measurement of transitions between the two components in a slit jet-cooled sample using a frequency comb-referenced extended cavity diode laser. This spectrum was originally detected in a hot source by Fourier transform near-infrared spectroscopy, but low-J transitions were unresolved at that time.

Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Work by N. E. Shafer-Ray was performed with support from the National Science Foundatation award NSF-0855431. J.-U. Grabow ackonwledges funding from the Deutsche Forschungsgemeinschaft and the Land Niedersachsen.