High-precision laser spectroscopy of the CO A${}^1\Pi$ - X${}^1{\Sigma }^{+}$ (2,0), (3,0) and (4,0) bands

Abstract

High-precision two-photon Doppler-free frequency measurements have been performed on the CO A${}^1\Pi$ - X${}^1{\Sigma }^{+}$ fourth-positive system (2,0), (3,0), and (4,0) bands. Absolute frequencies of forty-three transitions, for rotational quantum numbers up to $J=5$, have been determined at an accuracy of $1.6\times 10^{-3}$ cm${}^{-1}$, using advanced techniques of two-color 2+1' resonance-enhanced multi-photon ionization, Sagnac interferometry, frequency-chirp analysis on the laser pulses, and correction for AC-Stark shifts. The accurate transition frequencies of the CO A${}^1\Pi$ - X${}^1{\Sigma }^{+}$ system are of relevance for comparison with astronomical data in the search for possible drifts of fundamental constants in the early universe. The present accuracies in laboratory wavelengths of $\Delta \lambda /\lambda =2\times 10^{-8}$ may be considered exact for the purpose of such comparisons.

arXiv comment13 pages, 6 figures, The Journal of Chemical Physics (2015) accepted

References in corpus (1)

• The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio

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• Test of quantum chemistry in vibrationally-hot hydrogen molecules
• Spectroscopy and perturbation analysis of the A${}^1\Pi$(v=0) state of ${}^{13}$C${}^{16}$O
• Precision spectroscopy and comprehensive analysis of perturbations in the $A{}^1\Pi (v=0$) state of ${}^{13}$C${}^{18}$O