Excitation into $3p^{5}5p$ levels from the metastable levels of Ar

Measurements of cross sections for electron-impact excitation out of the $J=0$ and $J=2$ $3p^{5}4s$ metastable levels of argon into nine of the ten levels of the $3p^{5}5p$ manifold are presented in the energy range from threshold to $10\mathrm{eV}$. A mixed target of atoms in both metastable levels was created by a hollow cathode discharge. Laser quenching was used to depopulate either one of the metastable levels, allowing separate measurements of the cross sections from each of the two metastable levels. Unlike the metastable excitation cross sections into $3p^{5}4p$ levels, the cross sections into the $3p^{5}5p$ levels are not found to be proportional to optical oscillator strengths.

Figure 1

Partial energy level diagram of relevant Ar energy levels. Rectangles represent groups of levels within each configuration.

Figure 2

Quenching results for $3p_9$ and $3p_1$ levels. In the lower graph some of the points have been offset for clarity.

Figure 3

Apparent cross sections for excitation into $3p^{5}5p$ levels from the $J=2$ $1s_5$ metastable level. Error bars are statistical only and do not include the absolute calibration uncertainty of $\pm 40\%$, but they reflect the uncertainty of the relative values and energy dependence of the cross sections.

Figure 4

Apparent cross sections for excitation into $3p^{5}5p$ levels from the $J=0$ $1s_3$ metastable level. Error bars are statistical only and do not include the absolute calibration uncertainty of $\pm 40\%$, but they reflect the uncertainty of the relative values and energy dependence of the cross sections.

Figure 5

Generalized oscillator strengths for the $1s_5\to 2p_9$ and $1s_5\to 3p_9$ excitation processes.

Figure 6

Product of the $P_{4s}\left(r\right)P_{4p}\left(r\right)$ and $P_{4s}\left(r\right)P_{5p}\left(r\right)$ radial wave functions.