Core effect on the diamagnetic spectrum of barium Rydberg states

Abstract

We study the core effect of nonhydrogenic alkaline-earth-metal barium in its diamagnetic spectrum by one photon transition from the ground state 6s 2 1 S 0 experimentally and theoretically. The non-Coulombic potential of the ion core introduces an extra energy shift compared with hydrogen and a level anticrossing between different n manifolds, characterized by the quantum defect of the concerned angular momentum states. With a complex rotation coordinate technique and a B-spline expansion method, we develop a matrix-form Hamiltonian based on an effective potential incorporating the angular-dependent quantum defect into the angular rotation term. The nonhydrogen core effects are investigated by sweeping the quantum defects of different channels in the calculation. Results show that quantum defects of p and f states have a undeniable effect on the intensities and positions of the spectral lines, although barium is closely hydrogenlike in the energy range examined. The anticrossing spectral lines are also identified with the aid of theoretical calculations. The calculations are in good agreement with the experimental observations.

Non-linear spectral splitting of Rydberg sodium in external fields

“…The experiment is performed on the same apparatus described previously, [21,22] here we just summarize the main features and improvements. A sodium atomic beam spouted from a resistance-heated oven travels to the interaction region after being collimated by two pin-holes with diameters of about 2 mm.…”

“…The calculation has been introduced in detail in our previous works, [20,21,24] here we only summarize the main steps. In the presence of external parallel electric and magnetic fields oriented along the z-axis, in atomic units by the convention, the non-relativistic Hamiltonian H for the Rydberg sodium atom can be written as follows: [20]…”

“…All the spectra are calculated with our newly developed quantum method combining the quantum defect orbit model and the B-Spline basis. [20,21]…”

Nonlinear spectroscopy of barium in parallel electric and magnetic fields

“…[5,6] For an atom in a strong magnetic field, the diamagnetic term in the Hamiltonian makes the system non-separable even for a hydrogen atom. [2] Researchers have developed a semiclassical method [7,8] and quantum calculation [9,10] to treat this problem and explain the correlative experiments. [11,12] Although there is a quadratic term in the Hamiltonian, the atom in a magnetic field has a simpler structure [13,14] than the Stark spectrum [6,15] for its higher symmetry.…”

Electron Dynamics of Atoms in Parallel Electric and Magnetic Fields

“…The numerical calculation is carried out based on the well-developed full quantum method. [9,10] The energy range examined in this study is from −47 cm −1 to −39 cm −1 and the magnetic field strength is 0.57 T, where the spectrum is on the edge of inter-𝑛 mixing. The electric field is swept from 0 to 23 V/cm, with the spectrum evolving from inter-𝑙 mixing to deep inter-𝑛 mixing.…”