标题： 铷$_2$的电场电离分子里德伯态的电离能 显示英文标题

标题： Ionization Energy of Rb$_2$ by electric field-ionization of molecular Rydberg states

摘要： 我们通过超音速束中的共振增强双光子电离测定了$^{85}\text{Rb}_2$分子的电离能。第一个光子激发$X^1\Sigma_g^+ (v_X = 0)\rightarrow B^1\Pi_u (v_B = 2)$转换，而第二个光子波数在 16720 cm$^{-1}$-16750 cm$^{-1}$范围内扫描，从而产生由电场提取并由质谱记录的 Rb$_2^+$离子的结构化光谱。 我们将电离信号的开始建模为$18 V/cm$和$180 V/cm$之间的电场强度的函数，导致 Rb$_2$电离能$E_i = 31497.3 \pm 0.6 $cm$^{-1}$，以及 Rb$_2^+$基态的解离能$D_0 = 6158.2 \pm 0.6$cm$^{-1}$。 我们测量的值$E_i$被发现比 Bellos 等人实验中报告的值大$149.3$cm$^{-1}$。 [Phys. Rev. A 87, 012508 (2013)]。 我们对$D_0$的值与我们使用量子化学方法进行的理论确定结果一致。 使用一个简单的理论模型，我们将电离谱的不均匀间隔结构归因于属于几个系列的分子里德伯能级，这些系列收敛到 Rb$_2^+$的最低振动水平。 显示英文摘要

摘要： We report the measurement of the ionization energy of the $^{85}\text{Rb}_2$ molecule through resonantly enhanced 2-photon ionization in a supersonic beam. The first photon excites the $X^1\Sigma_g^+ (v_X = 0)\rightarrow B^1\Pi_u (v_B = 2)$ transition, while the second photon wavenumber is scanned over the 16720 cm$^{-1}$-16750 cm$^{-1}$ range, thus yielding a structured spectrum of Rb$_2^+$ ions extracted by an electric field and recorded by mass spectrometry. We modeled the onset of the ionization signal as a function of the electric field strength between $18 V/cm$ and $180 V/cm$, leading to the Rb$_2$ ionization energy $E_i = 31497.3 \pm 0.6 $cm$^{-1}$, and to the dissociation energy of the Rb$_2^+$ ground state $D_0 = 6158.2 \pm 0.6$ cm$^{-1}$. Our measured value $E_i$ is found to be $149.3$ cm$^{-1}$ larger than the one reported in the experiment by Bellos et al. [Phys. Rev. A 87, 012508 (2013)]. Our value of $D_0$ agrees with our theoretical determination using a quantum chemistry approach. Using a simple theoretical model, we assign unevenly spaced structures of the ionization spectrum to molecular Rydberg levels belonging to several series that converge to the lowest vibrational levels of Rb$_2^+$.