Detection of Rydberg states in atomic uranium using time-resolved stepwise laser photoionization

Abstract

We report the first observation of perturbed and unperturbed Rydberg progressions of atomic uranium. Highlying levels within 1000 cm ' of the ionization limit were accessed by time-resolved stepwise excitation using dye laser pulses tuned to resonant transitions. Atoms excited to these states were then photoionized by intense infrared radiation from a pulsed CO2 laser. The resultant photoion production was monitored. By delaying the infrared ionizing pulse, and thus discriminating against the shorter-lived valence states, we preferentially detected Rydberg levels with principal quantum numbers n exceeding 60. Series convergence yields a value of the ionization limit of 6.1941~0.0005 eV, in fair agreement with the value of 6.1912~0.0025 eV obtained in photoionization studies. Ab initio calculations indicate that the unperturbed series belong to highly excited 5f'7s'np and nf configurations.

First Determination of the Ionization Potential of Actinium and First Observation of Optical Transitions in Ferminm

“…Taking an offset of 12 V/cm into account, due to the penetration of electric fields into the interaction region, results in a perfect fit of a straight line to the ionization thresholds Wth as a function of the square root of the electrical field strengths, see [10][11][12][13]. The uncertainties for the Mainz values are statistical errors given as two standard deviations (20") derived from the least-squares fits including weighted errors for each data point.…”

Measurement of holmium Rydberg series through magneto-optical trap depletion spectroscopy

“…Studies of the Rydberg spectra of neutral rare earth elements have been limited to date, with initial measurements of the ionization potentials for the full range of lanthanides [11] and actinides [12] and energy resolved Rydberg states for La [13], Eu [14], Dy [15], Lu [16], Gd [17], Sm [18], Th [19], Ce [20], Yb [21], Ac [22], Pu [23] and U [24]. In this paper we present the first high resolution spectroscopy of the 4f 11 6sns and 4f 11 6snd odd-parity Rydberg states of Ho in the range n = 40 − 101 using depletion measurements * hostetter@wisc.edu † msaffman@wisc.edu on a magneto optical trap (MOT).…”

LASER PHOTOIONIZATION SENSOR OF THE SEPARATING HEAVY ISOTOPES AND NUCLEAR ISOMERS: SELECTIVE IONIZATION BY DC ELECTRIC AND LASER FIELD (U, Tm)

“…We considered a scheme for the laser separation and sensing the uranium and thulium isotopes. All necessary excitation and ionization constants for solution of the density matrice equations system are calculated within above described model and methods [7][8][9]23,24]. The laser photoionization scheme for U isotopes included the following steps: i).…”

“…In real multi-electron atom it is necessary to account for the influence of the electron shells, which results in the changing the potential barrier and wave functions. To define the wave functions and electron state energies in an electric field, one needs to carry out the diagonalization of energy matrice, calculated between states with the same n [7][8][9]28]. The diagonalization of the complex energy matrix leads to complex energy correction: ReE -iГ/2, where Re E is the level shift and Г is the level width, including the radiation and autoionization widths simultaneously.…”

“…Now it is well known that the laser photoionization method is one of the most perspective methods for the sensing single atomic particles, separating isotopes, nuclear isomers and nuclear reactions products (c. f. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]). The standard laser ionization sensor scheme may be realized with using a scheme of the multi-step excitement and ionization of atoms by laser pulse.…”