Three-step resonance excitation to autoionization states is a promising isotope-selective ionization technique for atomic strontium (Sr). We measured for the first time the DC Stark shifts of ten Rydberg levels ($n_{\text{eff}}\sim 36-39,$ $50-55$) of ${}^{88}$Sr converging to the 4d ${}^2$D${}_{3/2}$ limit using the 5s${}^2{}^1$S${}_0$ $\to$ 5s5p ${}^1$P${}_1^{\circ }$ $\to$ 5p${}^2{}^1$D${}_2$ $\to$ (4d ${}^2$D${}_{3/2}$ Rydberg series) transition pathway. The polarizability $\alpha$ of each level was evaluated to be $\left|\alpha \right|\sim {10}^{-30}-{10}^{-28}$ [C${}^2$$·$m${}^2$$·$J${}^{-1}$] depending on the effective principal quantum number $n_{\text{eff}},$ which indicates that the external electric field $E$ in the ionization region should be of the order of 0.1 V/cm or less to suppress its effect on the observed spectra. Our experimental data on the DC Stark shift and polarizability of the Rydberg levels are useful for future isotope-selective detection of the radioisotope ${}^{90}$Sr using three-step resonance excitation.

三步共振激发到自电离态是一种用于原子锶（Sr）的有前途的同位素选择性电离技术。我们首次测量了十个里德伯格水平的直流斯塔克频移（${ñ}_{\text{效}}〜36-39，$ $50-55$） 的 ${}^{88}$融合至4d的sr ${}^2$d${}_{3/2}$ 限制使用5秒${}^2{}^{\mathrm{1个}}$小号${}_0$ $\to$ 5秒5秒 ${}^{\mathrm{1个}}$P${}_{\mathrm{1个}}^{\circ }$ $\to$ 5p${}^2{}^{\mathrm{1个}}$d${}_2$ $\to$ （4天 ${}^2$d${}_{3/2}$Rydberg系列）过渡途径。极化率$\alpha$ 每个级别的评估为 $\left|\alpha \right|〜{10}^{-30}-{10}^{-28}$ [C${}^2$$·$米${}^2$$·$Ĵ${}^{-\mathrm{1个}}$]取决于有效的主量子数 ${ñ}_{\text{效}}，$ 表示外部电场 $Ë$在电离区域中的“α”应约为0.1 V / cm或更小，以抑制其对观察到的光谱的影响。我们关于Rydberg能级的DC Stark位移和极化率的实验数据对于放射性同位素的未来同位素选择性检测很有用${}^{90}$锶采用三步共振激发。