Experimental study of the Ca2 1S+1S asymptote

Abstract

The filtered laser excitation technique was applied for measuring transition frequencies of the Ca${}_2$ B-X system from asymptotic levels of the X${}^1{\Sigma }_{\mathrm{g}}^{+}$ ground state reaching $v^{\prime \prime }=38$. That level has an outer classical turning point of about 20~Åwhich is only 0.2 \rcm below the molecular ${}^1$S${+}^1$S asymptote. Extensive analysis of the spectroscopic data, involving Monte Carlo simulation, allowed for a purely experimental determination of the long range parameters of the potential energy curve. The possible values of the s-wave scattering length could be limited to be between 250$a_0$ and 1000$a_0$.

10 pages, 7 figures