The analysis of the vacuum spark spectrum of erbium in the wavelength region 705 - 2460 Å has been extended. A total of 1022 spectral lines are newly identified as transitions between the low lying configurations $4f^{11}$, $4f^{10}5d$, $4f^{10}6s$ and $4f^{10}6p$ of the Er${}^{3+}$ ion (Er IV), in addition to the confirmed previously identified 582 ones. The extended analysis has led to the determination of 168 new energy levels in Er${}^{3+}$, in addition to the 120 previously known ones. Energy values have been optimised by a least-squares procedure based on an increased number of measured wavelengths, resulting in a reduction of their uncertainties. Parametric calculations have been performed using the Cowan codes, in which radial integrals are parameters fitted by least-squares minimisation of the differences calculated - experimental energies. The increased number of experimentally known levels leads to better defined parameters and improved predictions of unknown energy levels and electric dipole transition probabilities. Fitted parameters are compared with ab initio Hartree-Fock integrals including relativistic corrections (HFR). The mean errors of the fits are respectively 51 cm${}^{-1}$ for 65 known levels of the odd configurations $4f^{11}$ + $4f^{10}6p$ with 9 free parameters, and 53 cm${}^{-1}$ for 223 known levels of the even configurations $4f^{10}5d$ + $4f^{10}6s$ with 17 free parameters.

波长范围 705 - 2460 Å 中铒的真空火花光谱分析已得到扩展。共有 1022 条谱线被新识别为低位构型之间的过渡$4F^{11}$, $4F^{10}5d$, $4F^{10}6秒$ 和 $4F^{10}6磷$ 尔的${}^{3+}$离子（Er IV），除了之前确认的 582 个。扩展分析导致确定了 Er 中的 168 个新能级${}^{3+}$，除了之前已知的 120 个。能量值已通过基于增加的测量波长数量的最小二乘法进行优化，从而降低了它们的不确定性。参数计算已使用 Cowan 代码执行，其中径向积分是通过最小二乘法最小化计算的差异 - 实验能量拟合的参数。实验已知能级数量的增加导致更好地定义参数并改进对未知能级和电偶极子跃迁概率的预测。拟合参数与包括相对论校正 (HFR) 的从头算Hartree-Fock 积分进行比较。拟合的平均误差分别为 51 cm${}^{-1}$ 对于奇数配置的 65 个已知水平 $4F^{11}$ + $4F^{10}6磷$ 具有 9 个自由参数和 53 cm${}^{-1}$ 对于 223 个已知水平的偶数配置 $4F^{10}5d$ + $4F^{10}6秒$ 有 17 个自由参数。