Excited States Of Neutral Atoms Research Articles

Excited states time evolution on a laser-ablated molybdenum plume

The dynamics of the excited states on a laser-ablated Mo plume was studied, both in air and in vacuum, by emission spectroscopy along the plume expansion axis. The emission related to ionized atoms occurs in the beginning of the plume expansion, near the metal surface, and is predominantly ultraviolet emission. In the middle of the plasma plume, it takes place the electron transitions between excited states of neutral atoms, and in the end of the plume, the visible emission is to transitions to the ground state of neutral molybdenum atoms. It was possible to determine plume parameters such as plasma expansion velocity of (5.0 ± 0.7) km/s at atmospheric pressure and (4.0 ± 0.7) km/s in vacuum, and the plasma duration that was (160 ± 14) ns at atmospheric pressure and (138 ± 18) ns in vacuum.

Gaussian basis sets for low-lying excited states of neutral atoms with 2 ≤ Z ≤ 36

The improved generator coordinate Hartree–Fock method is used to generate Gaussian basis sets for low-lying excited states of neutral atoms from He (Z = 2) to Kr (Z = 36). Then, excitation energies and orbital energies of the outermost orbitals of each symmetry are calculated and compared with the corresponding values obtained with numerical Hartree–Fock calculations. Besides this, the basis sets for Be (3P) and F (2P) are contracted by a standard procedure and, then, enriched with polarization functions. From these basis sets, total energies, dissociation energy, and bond length for BeF are calculated and compared with results obtained with other basis sets and with experimental values. The sets for He–Kr are useful in constructing basis sets for molecular calculations. Key words: improved generator coordinate Hartree–Fock method, Gaussian basis sets, low-lying excited states, neutral atoms.

Ground states of H, He,…, Ne, and their singly positive ions in strong magnetic fields: The high-field regime

The electronic structure of the ground state and some excited states of neutral atoms with the nuclear charge numbers $1<~Z<~10$ and their singly positive ions are investigated by means of our two-dimensional mesh Hartree-Fock method for strong magnetic fields $0.5<~\ensuremath{\gamma}<~10000.$ For $\ensuremath{\gamma}=10000$ the ground-state configurations of all the atoms and ions considered are given by fully spin-polarized configurations of single-electron orbitals with magnetic quantum numbers ranging from $m=0$ to $m=\ensuremath{-}N+1,$ where N is the number of the electrons. Focusing on the fully spin-polarized situation, we provide critical values of the magnetic-field strength for which crossovers with respect to the spatial symmetries of the ground state take place. It is found that the neutral atoms and singly charged positive ions with $2<~Z<~5$ have one fully spin-polarized ground-state configuration, whereas for $6<~Z<~10$ one intermediate fully spin-polarized configuration with an orbital of ${2p}_{0}$ type occurs.

Numerical Hartree-Fock energies of low-lying excited states of neutral atoms with 19⩽ Z⩽36

Numerical Hartree-Fock calculations have been performed for all 209 states arising from the 4s 23d m and 4s 13d m+1 configurations for the atoms Sc to Zn. Among the various properties and states, total energies, orbital energies and the mean values of r of the outermost orbitals of each symmetry are presented and discussed for the lowest and the highest states of the respective configurations as well as the ground states. The 51 excited states for K, Ca and Ga Kr are also examined. The results could be useful as a calibration for constructing basis sets for molecular calculations.

Numerical Hartree–Fock energies of low-lying excited states of neutral atoms with Z≤18

Numerical Hartree–Fock calculations have been performed for low-lying excited states of the neutral atoms from He to Ar. Total energies, orbital energies, and the mean values of r of the outermost orbitals of each symmetry are tabulated as an aid to calibration of algebraic basis sets.

Cross Sections for Photoionization from Valence-Electron States

In order to study recombination processes in gaseous nebulae, one requires the coefficients for radiative recombination to many excited states of neutral atoms and positive ions. These may be calculated as functions of electron temperature once the corresponding photoionization cross sections are known. For photoionization from valence-electron states a general formula has been obtained using a method which is an extension of that used by Bates and Damgaard for bound-bound transition probabilities.