This paper summarizes a long series of experiments that have been done on Rydberg states of Rb. The basic experimental technique that has been used is atomic-beam laser spectroscopy which allows both low-resolution and high-resolution studies. Excitation of Rydberg states is provided by single-photon absorption from a suitably frequency-doubled rhodamine $6G$ tunable laser. Detection is done by field ionization and ion counting. These techniques have allowed us to study the critical ionizing field, which has been found to follow classical, hydrogenic behavior closely. Rydberg states of Rb have been observed from $n=28$ up to $n>100$ . High-resolution spectroscopic studies have led to measurement of the fine structure for $\mathrm{np}$ levels located between $n=28$ and $n=60$ , as well as the isotope shift of the ground state, $\ensuremath{\delta}\ensuremath{\nu}=(172\ifmmode\pm\else\textpm\fi{}15)$ MHz. Anomalies in the intensity ratio of the doublet $5s\ensuremath{-}np$ transitions have been observed and interpreted as relativistic effects. Perturbations by weak and strong dc electric field are reported. In the case of weak electric fields it is possible to evaluate the polarizability. In the case of strong dc electric fields, new phenomena have been observed and analyzed. We also find experimental evidence of selective photoionization in the presence of an appropriate dc electric field, which could have some applications in laser isotope separation. Finally, we give the preliminary results of an experiment on the effect of a strong nonresonant electromagnetic field on high-lying Rydberg states.This paper summarizes a long series of experiments that have been done on Rydberg states of Rb. The basic experimental technique that has been used is atomic-beam laser spectroscopy which allows both low-resolution and high-resolution studies. Excitation of Rydberg states is provided by single-photon absorption from a suitably frequency-doubled rhodamine $6G$ tunable laser. Detection is done by field ionization and ion counting. These techniques have allowed us to study the critical ionizing field, which has been found to follow classical, hydrogenic behavior closely. Rydberg states of Rb have been observed from $n=28$ up to $n>100$. High-resolution spectroscopic studies have led to measurement of the fine structure for $\mathrm{np}$ levels located between $n=28$ and $n=60$, as well as the isotope shift of the ground state, $\ensuremath{\delta}\ensuremath{\nu}=(172\ifmmode\pm\else\textpm\fi{}15)$ MHz. Anomalies in the intensity ratio of the doublet $5s\ensuremath{-}np$ transitions have been observed and interpreted as relativistic effects. Perturbations by weak and strong dc electric field are reported. In the case of weak electric fields it is possible to evaluate the polarizability. In the case of strong dc electric fields, new phenomena have been observed and analyzed. We also find experimental evidence of selective photoionization in the presence of an appropriate dc electric field, which could have some applications in laser isotope separation. Finally, we give the preliminary results of an experiment on the effect of a strong nonresonant electromagnetic field on high-lying Rydberg states.

Physical Review AAug 1, 197969 citations

Cold Atom targets in the femtosecond laser field

Renyuan Li, Junyang Yuan, Xinya Hou +10 more

We study photoionization of cold rubidium atoms in a strong infrared laser field using a magneto-optical trap (MOT) recoil ion momentum spectrometer. Three types of cold rubidium target are provided, operating in two-dimension (2D) MOT, 2D molasses, and 3D MOT with densities in the orders of $10^7$ atoms/cm $^3$ , $10^8$ atoms/cm $^3$ , and $10^9$ atoms/cm $^3$ , respectively. The density profile and the temperature of 3D MOT are characterized using the absorption imaging and photoionization. The momentum distributions of Rb $^+$ created by absorption of two- or three-photon illuminate a dipole-like double-peak structure, in good agreement with the results in the strong field approximation. The yielding momentum resolution of $0.12 \pm 0.03$ a.u. is achieved in comparison with theoretical calculations, exhibiting the great prospects for the study of electron correlations in alkali metal atoms through interaction with strong laser pulses.We study photoionization of cold rubidium atoms in a strong infrared laser field using a magneto-optical trap (MOT) recoil ion momentum spectrometer. Three types of cold rubidium target are provided, operating in two-dimension (2D) MOT, 2D molasses, and 3D MOT with densities in the orders of $10^7$ atoms/cm$^3$, $10^8$ atoms/cm$^3$, and $10^9$ atoms/cm$^3$, respectively. The density profile and the temperature of 3D MOT are characterized using the absorption imaging and photoionization. The momentum distributions of Rb$^+$ created by absorption of two- or three-photon illuminate a dipole-like double-peak structure, in good agreement with the results in the strong field approximation. The yielding momentum resolution of $0.12 \pm 0.03$ a.u. is achieved in comparison with theoretical calculations, exhibiting the great prospects for the study of electron correlations in alkali metal atoms through interaction with strong laser pulses.

arXiv:1806.06510Jun 18, 20180 citations

An analysis on the efficient laser photoionization of atoms

K. Katoh, Shuichi Hasegawa, Akihiro Suzuki

Annals of Nuclear EnergyJan 1, 19901 citation

Dynamic Double-Slit Experiment in a Single Atom

James Pursehouse, Andrew James Murray, Jonas Wätzel +1 more

A single-atom "double-slit" experiment is realized by photoionizing rubidium atoms using two independent low power lasers. The photoelectron wave of well-defined energy recedes to the continuum either from the 5P or 6P states in the same atom, resulting in two-path interference imaged in the far field using a photoelectron detector. Even though the lasers are independent and not phase locked, the transitions within the atom impart the phase relationship necessary for interference. The experiment is designed so that either 5P or 6P states are excited by one laser, before ionization by the second beam. The measurement cannot determine which excitation path is taken, resulting in interference in wave-vector space analogous to Young's double-slit studies. As the lasers are tunable in both frequency and intensity, the individual excitation-ionization pathways can be varied, allowing dynamic control of the interference term. Since the electron wave recedes in the Coulomb potential of the residual ion, a quantum model is used to capture the dynamics. Excellent agreement is found between theory and experiment.A single-atom "double-slit" experiment is realized by photoionizing rubidium atoms using two independent low power lasers. The photoelectron wave of well-defined energy recedes to the continuum either from the 5P or 6P states in the same atom, resulting in two-path interference imaged in the far field using a photoelectron detector. Even though the lasers are independent and not phase locked, the transitions within the atom impart the phase relationship necessary for interference. The experiment is designed so that either 5P or 6P states are excited by one laser, before ionization by the second beam. The measurement cannot determine which excitation path is taken, resulting in interference in wave-vector space analogous to Young's double-slit studies. As the lasers are tunable in both frequency and intensity, the individual excitation-ionization pathways can be varied, allowing dynamic control of the interference term. Since the electron wave recedes in the Coulomb potential of the residual ion, a quantum model is used to capture the dynamics. Excellent agreement is found between theory and experiment.

arXiv:1901.05074Physical Review LettersFeb 8, 20190 citations

Direct double photoionization in atoms

Z. Liu

Cambridge University Press eBooksAug 10, 199813 citations

6G

tunable laser. Detection is done by field ionization and ion counting. These techniques have allowed us to study the critical ionizing field, which has been found to follow classical, hydrogenic behavior closely. Rydberg states of Rb have been observed from

n=28

up to

n>100

. High-resolution spectroscopic studies have led to measurement of the fine structure for

\mathrm{np}

levels located between

n=28

and

n=60

, as well as the isotope shift of the ground state, $\ensuremath{\delta}\ensuremath{\nu}=(172\ifmmode\pm\else\textpm\fi{}15)$ MHz. Anomalies in the intensity ratio of the doublet $5s\ensuremath{-}np$ transitions have been observed and interpreted as relativistic effects. Perturbations by weak and strong dc electric field are reported. In the case of weak electric fields it is possible to evaluate the polarizability. In the case of strong dc electric fields, new phenomena have been observed and analyzed. We also find experimental evidence of selective photoionization in the presence of an appropriate dc electric field, which could have some applications in laser isotope separation. Finally, we give the preliminary results of an experiment on the effect of a strong nonresonant electromagnetic field on high-lying Rydberg states.

10^7

atoms/cm

^3

10^8

atoms/cm

^3

, and

10^9

atoms/cm

^3

, respectively. The density profile and the temperature of 3D MOT are characterized using the absorption imaging and photoionization. The momentum distributions of Rb

^+

created by absorption of two- or three-photon illuminate a dipole-like double-peak structure, in good agreement with the results in the strong field approximation. The yielding momentum resolution of

0.12 \pm 0.03

a.u. is achieved in comparison with theoretical calculations, exhibiting the great prospects for the study of electron correlations in alkali metal atoms through interaction with strong laser pulses.