Figure 1

Some relevant energy levels and transitions in atomic argon.Reuse & Permissions

Figure 2

Potentials associated with the cooling transition in argon. (a) Singly excited potentials connected to the (4$s[3/2]{}_2+4p[5/2]{}_3$) asymptote. (b) Singly and doubly excited potentials connected to the (4$s[3/2]{}_2+4p[5/2]{}_3$) and (4$p[5/2]{}_3+4p[5/2]{}_3$) asymptotes, respectively. An asterisk labels the same two singly excited curves in both (a) and (b). Solid curves represent our calculated dipole-dipole potentials. Dashed lines in (b) are potentials of the form $C_5/R^5$ with $C_5=100$, 1000 and 10 000 a.u., respectively (left to right). Various shades of gray are used to distinguish curves with different values of $\Omega$ (which is the projection of total electronic angular momentum onto the internuclear axis). The unit of $a_0$ is the Bohr radius (0.0529 nm). As mentioned near the end of the paper, large Franck-Condon factors for transitions from the singly to doubly excited curves in (b) may increase the double-excitation rate for $20a_0<R<80a_0$.Reuse & Permissions

Figure 3

Timing schematic for photoassociative spectroscopy experiment.Reuse & Permissions

Figure 4

Photoassociative ionization spectrum for Ar* near the ($4s[3/2]{}_2+4p[5/2]{}_3$) asymptote. Spectra are plotted in order of increasing probe intensity starting with the lowest value on the bottom. $I_{\mathrm{sat}}$ is the atomic saturation intensity.Reuse & Permissions

Figure 5

Photoassociative ionization spectrum for Ar* near the ($4s[3/2]{}_2+4p[5/2]{}_3$) asymptote. Spectra are plotted in order of increasing probe intensity starting with the lowest value on the bottom. $I_{\mathrm{sat}}$ is the atomic saturation intensity.Reuse & Permissions