High resolution and sub-Doppler Fourier transform spectroscopy: Iodine molecular fluorescence excited by the 514.5 and 501.7 nm Ar+ laser lines

Fluorescence from the I2 B O+u state, excited by the 514.5 and 501.7 nm cw Ar+ laser lines, is recorded using a high resolution Fourier transform spectrometer. Spectra are obtained with both multimode (6 GHz) and single mode (<100 MHz) Ar+ lasers, the latter spectra exhibiting reduced Doppler width. B O+u−X 1Σ+g fluorescence is recorded at 1 mK precision for v″=10–100, eQq″ quadrupole constants are obtained (±5%) from measured linewidths, broadening of quasibound X 1Σ+g rotational levels above the rotationless X 1Σ+g dissociation limit is observed, and perturbations of X 1Σ+ v″⩾92 by two previously unobserved long range I2 molecular states are detected. These two states, 0+g and 1g, which dissociate into two 2P3/2 I atoms, are also observed directly in the fluorescence spectrum. This paper presents illustrative examples; constants and a complete analysis will appear subsequently.