Photoassociation, photoluminescence, and collisional dissociation of the Sr2 dimer

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Abstract
We report observations and analysis of the laser-excited photoluminescence of Sr2. The spectra contains some discrete molecular line spectra, but is dominated by extensive, deeply modulated continua characteristic of bound–free transitions of excimer systems. Dye laser and argon laser excitation of the Sr2 dimer is used. Some of the spectra is attributed to fluorescence from dimers created by laser induced photoassociation of free Sr atoms. Techniques are developed to obtain Morse potential parameters by computer modeling of the observed spectra. We find for the X 1Σ+g state, De=1100±100 cm−1, ωe=39.6±1 cm−1; for the A 1Σ+u state, De=5460±100 cm−1, ωe=83±3 cm−1; and Re″−Re′=0.49±0.02 Å. Strong collision-induced predissociation is observed and attributed to a potential curve crossing. Cross sections for dissociation by argon are reported as a function of laser excitation wavelength.