Pressure Broadening of the Violet Triplet of Manganese in the Presence of Argon and Helium

The $\lambda 4030$ triplet of Mn ($3d^{5}4s^2$, ${}_{}{}^6{}_{}{}^{}S-3\mathrm{}{d}^{5}4s4p$, ${}_{}{}^6{}_{}{}^{}P°$) was studied in absorption under various pressures of argon and helium ranging in relative density from 1 to 30. Helium produced no shift while argon produced a linear red shift of 0.12 ${\mathrm{cm}}^{-1\mathrm{}}$/r.d. In the presence of both helium and argon, the half-widths were found to increase directly with increasing relative density of the perturbing gas. The $j=\frac{3}{2}, \frac{5}{2} \mathrm{and} \frac{7}{2}$ components are broadened in helium by 0.46, 0.50, and 0.47 ${\mathrm{cm}}^{-1\mathrm{}}$/r.d., respectively, while the same components are broadened in argon by 0.33, 0.36, and 0.30 ${\mathrm{cm}}^{-1\mathrm{}}$/r.d. The result for Mn/Ar indicates that the interatomic energies are proportional to the inverse sixth power of the interatomic distance, and that the difference in the interaction constants for the ground state ${}_{}{}^6{}_{}{}^{}S$ and the excited states ${}_{}{}^6{}_{}{}^{}P$ of Mn in argon is 3×${10}^{-58\mathrm{}}$ erg ${\mathrm{cm}}^6$.