Oscillator strengths for in-shell (Δn=0) dipole transitions in Li- and Be-like sulfur

The foil-excitation method has been employed to determine lifetimes, transition probabilities, and $f$ values for $\Delta n=0\mathrm{}$ dipole transitions between the $n=2\mathrm{}$ states of the highly stripped ions, ${\mathrm{S}}^{12+}$ and ${\mathrm{S}}^{13+}$. The fine-two structure interval between the $J=\frac{1}{2} \mathrm{and} \frac{3}{2}$ levels of the $1s^{2}2p{}_{}{}^2{}_{}{}^{}P_{}^o{}_{}{}^{}$ term in ${\mathrm{S}}^{13+}$ was also determined, and the result confirms recent astrophysical observations.