Absolute measurement of the S(0) and S(1) lines in the electric quadrupole fundamental band of D2 around 3 µm

The electric quadrupole fundamental (v=1 <- 0) band of molecular deuterium around 3 mu m is accessed by cavity ring-down spectroscopy using a difference-frequency-generation source linked to the Cs-clock primary standard via an optical frequency comb synthesizer. An absolute determination of the line position and strength is reported for the first two transitions (J=2 <- 0 and J=3 <- 1) of the S branch. An accuracy of 6 x 10(-8) is achieved for the line-center frequencies, which improves by a factor 20 previous experimental results [A. R. W. McKellar and T. Oka, Can. J. Phys. 56, 1315 (1978)]. The line strength values, measured with 1% accuracy, are used to retrieve the quadrupole moment matrix elements which are found in good agreement with previous theoretical calculations [A. Birnbaum and J. D. Poll, J. Atmos. Sci. 26, 943 (1969); J. L. Hunt, J. D. Poll, and L. Wolniewicz, Can. J. Phys. 62, 1719 (1984)]. (C) 2010 American Institute of Physics. [doi:10.1063/1.3493393]