Energy and lifetime measurements in heliumlike and lithiumlike phosphorus

The x-ray energies in the transitions to the ground state from the $2{}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$ and $2{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ levels in heliumlike phosphorus and from the $2{}_{}{}^4{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}$ level in lithiumlike phosphorus have been determined by using a Doppler-tuned x-ray spectrometer. The experimental results $E(2\mathrm{}{}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}-1\mathrm{}{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{})=(2142.3\mathrm{}\pm 1.2)$ eV, $E(2\mathrm{}{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}-1\mathrm{}{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{})=(2126.7\mathrm{}\pm 1.2)$ eV, and $E({}_{}{}^4{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}-{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{})=(2112.3\mathrm{}\pm 1.2)$ eV are in good agreement with theoretical predictions. The mean life of the $2{}_{}{}^4{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}$ and $2{}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$ states have also been measured by the beam-foil time-of-flight method. The experimental values $\tau \left(2\mathrm{}{}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}\right)=(3.6\mathrm{}\pm 0.1)\times {10}^{-9\mathrm{}}$ s and $\tau \left(2\mathrm{}{}_{}{}^4{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}\right)=(1.2\mathrm{}\pm 0.1)\times {10}^{-9\mathrm{}}$ s are in agreement with theoretical predictions.