Rydberg States Of Barium Research Articles

Stark manifolds of barium Rydberg states

In a CW laser-atomic beam experiment Stark manifolds in barium originating from the Rydberg states 6s40f1F3, 6s40g1,3G4,3G5 and 6s40h1,3H5 have been studied. Accurate quantum defect values for higher orbital angular momentum states (l=6, 7) have been determined. The Stark manifolds are also calculated by diagonalization of the energy matrix in the presence of an external electric field. Good agreement between experiment and calculations is obtained.

Autoionization inhibited by internal interferences.

We have measured the linewidths of ${[5{d}_{\frac{3}{2}}{n}_{2}{d}_{\frac{3}{2}}]}_{J=0}$ autoionizing Rydberg states of barium with principal quantum numbers ranging between ${n}_{2}=14$ and ${n}_{2}=100$. Dramatic deviations of the autoionization rates from the normal ${n}_{2}^{*\ensuremath{-}3}$ scaling law have been observed. Whereas the ${[5{d}_{\frac{3}{2}}60{d}_{\frac{3}{2}}]}_{J=0}$ level exhibits a linewidth $\ensuremath{\Gamma}$ (FWMH) as low as 6 MHz, higher (${n}_{2}\ensuremath{\approx}80$) members of this series are broadened up to 5 GHz. Autoionization is inhibited for principal quantum numbers ${n}_{2}\ensuremath{\approx}60$ because of configuration interaction between the ${[5{d}_{\frac{3}{2}}{n}_{2}{d}_{\frac{3}{2}}]}_{J=0}$ and ${[5{d}_{\frac{5}{2}}{n}_{3}{d}_{\frac{5}{2}}]}_{J=0}$ Rydberg series. This causes the state at ${n}_{2}=60$ to be metastable.

High-resolution studies on bound odd-parity Rydberg states in Ba I

A study of the detailed structure of the bound odd-parity Rydberg states of barium has been undertaken using a cw dye laser in combination with an atomic beam. Special attention has been paid to the 6snf configurations, of which the hyperfine structure has been analyzed in terms of a small set of parameters. In addition to an effective Slater-exchange integral, an effective spin-orbit interaction, and a contact hyperfine parameter, a new parameter representing two-body magnetic effects, has been introduced. The introduction of this new parameter is discussed in some detail. Good agreement between the calculated and experimental hyperfine energies is achieved in this way. © 1983 The American Physical Society.

High resolution spectroscopy on 6sns Rydberg states of barium

Extensive new data on perturbed and unperturbed levels of the 6s n s1S0 and 6s n s3S1 Rydberg series of Barium have been obtained in a high-resolution laser atomic-beam experiment. Special attention has been paid to the region aboven=15 where the3S1 series is strongly perturbed. The results on hyperfine energies and isotopic field shift ratios are compared with calculations using wavefunctions obtained from a Multi Channel Quantum Defect analysis. The applicability of various approximations to these wavefunctions is discussed. Good agreement between experiment and calculation is obtained.

Configuration interaction and singlet-triplet mixing probed by hyperfine structure of 6s14d1D2and3D1,2,3barium Rydberg states

The hyperfine structure of the 6s14d configuration of barium has been measured by optical-optical double resonance. From the observed positions for the hyperfine components of the 1D2 and 3D1,2,3 Rydberg states, the singlet and triplet character as well as the amount of admixture of the 5d7d perturbing configuration was deduced. Although agreeing qualitatively, the authors' results differ quantitatively from predictions made by multichannel quantum defect theory (MQDT).

Fine structure perturbations of hyperfine structure of 6snd3D2Rydberg states of barium

The hyperfine structure of 6snd 3D2 (11<or=n<or=27) Rydberg states of barium is reported. Between n=19 and 24 the hyperfine structure is dominated by perturbations due to the near-degenerate 6snd 3D1 fine structure component, masking the resonance in singlet-triplet mixing. The hyperfine structure can be analysed quantitatively to yield the singlet-triplet mixing parameter for the 3D2 Rydberg series, provided the fine structure splittings of the 3D states are known. Good agreement between the singlet-triplet mixing parameters of the 1D2 and 3D2 series was observed.

Optical-optical double resonance in barium

Using two CW dye lasers barium Rydberg states were populated by stepwise two-photon absorption via the 6s6p 1P1 intermediate level. Monitoring the transmission of the first laser beam, tuned to the resonance line, and scanning the second laser across the upper atomic transition, a greatly enhanced signal was observed. Taking optical pumping into account, a simple rate equation model can quantitatively describe the increase in sensitivity. This technique was applied to measure the hyperfine structure of the 6s15d 1D2 Rydberg state in barium.

Hyperfine structure of perturbed 6sns3S1Rydberg states of barium

The hyperfine structure of the 6sns 3S1 (14<or=n<or=23) Rydberg states of 135,137Ba has been measured. From these data the admixture of the 5d7d 3S1 and 1P1 perturbers into the Rydberg states has been derived. A comparison with isotope shift data proves the hyperfine structure of Rydberg states to be the more sensitive tool to detect small admixtures of doubly excited configurations.

Resonance in Singlet-Triplet Mixing in Two-Electron Systems Caused by Perturbing Configurations

The hyperfine structure of the $6snd^{1}D_{2}$ ($10&lt;~n&lt;~50$) Rydberg states of barium has been measured and analyzed in terms of singlet-triplet mixing. A dispersionlike resonant behavior of the mixing coefficient $\ensuremath{\Omega}$ was observed for barium and strontium in the vicinity of doubly excited configurations. In barium strong disagreement with multichannel-quantum-defect-theory wave functions was found. The present results are compared with the spin polarization and anisotropy of photoelectrons.

Systematic Investigation of Electron Densities at The Nucleus for Rydberg States of Barium

Isotope shifts of even Ba isotopes in transitions to $6sns^{1}S_{0}$ and $6snd^{1,3}D_{2}$ Rydberg states have been used to study systematically the change in electron density at the nucleus. For $n&gt;~11$ the total charge density at the origin approaches that of ${\mathrm{Ba}}^{+}$. Local perturbers strongly effect the electron density, and admixture coefficients can be derived which are in quantitative agreement with those from multichannel quantum defect theory.

Effects of electric fields on doubly excited autoionizing Rydberg states of barium

We report the effects of static electric fields on the doubly excited $6{p}_{\frac{1}{2}}\mathrm{nl}$ states of barium in the region ${n}^{*}=12$. Using a three-step laser excitation scheme we have measured the electric-field dependence of the positions and autoionization widths of the $6{p}_{\frac{1}{2}}\ensuremath{-}17s,16p,15d,12l (l=4\ensuremath{-}10),12f, \mathrm{and} 16s$ states at field values of up to 4.92 kV/cm. The photoexcitation spectra of the autoionizing states exhibit interference effects which are well understood and provide a better understanding of the character of these states in electric fields. The systematic study of the spectra and positions allows us to explain the field dependence of the autoionization widths in terms of electric-field mixing of the discrete portions of the auoionizing states. The relationship of these effects to dielectronic recombination rates of ions and electrons in plasma microfields is discussed.

Stark structure of barium Rydberg states

Observations of the Stark structure of barium for Rydberg states in the region of n=12 are presented. The Stark manifold includes a valence state which perturbs the 1D2 series. General features of the interaction of the valence and Rydberg states in the presence of the electric field are explained by simple arguments based on configuration mixing.