Two-photon transitions in the He$^{+}$ ion embedded in strongly-coupled plasmas

There have been considerable interests in atomic processes in weakly-coupled Debye plasmas [1]. Here, we report an investigation on two-photon transitions for the He$^{+}$ ion embedded in strongly-coupled plasmas. The 1$s$-2$s$, 1$s$-3$s$, 1$s$-4$s$, 1$s$-3$d$ and 1$s$-4$d$ two-photon transitions for the He$^{+}$ ion are studied. Using the ion-sphere (IS) model [2] for strongly-coupled plasmas, and employing B-spline basis to represent the wave functions, the absorption coefficients, resonant enhancement frequencies, and transparency frequencies for various ion-sphere radii are calculated using a pseudo-state method [3]. Detailed results will be presented at the meeting. [1] L. B. Zhao and Y. K. Ho, \textit{Phys. Plasmas} \textbf{11}, 1695 (2004); A. Yu and Y. K. Ho, \textit{Phys. Plasmas} \textbf{12}, 043302 (2005); S. Sahoo and Y. K. Ho, \textit{Phys. Plasmas} \textbf{13}, 063301 (2006); S. Kar and Y. K. Ho,\textit{ Phys. Plasmas} \textbf{15}, 013301 (2008); S. Paul and Y. K. Ho, \textit{Phys. Plasmas} \textbf{15}, 073301 (2008); \textit{Phys. Rev. A} \textbf{78}, 042711 (2008) [2] S. Ichimaru, \textit{Rev. Mod. Phys.} \textbf{54}, 1017 (1982). [3]. R. J. Drachman and A. K. Bhatia, and A. A. Shabazz, \textit{Phys. Rev.} A \textbf{42} 6333 (1990).