[en] The R-matrix approach to the description of autoionization in photoionization is outlined. Recent developments allowing the photoionization of excited states and heavy atoms to be considered are illustrated by calculations carried out over the last few years. The near term prospects of the method are discussed. 18 references, 5 figures

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[en] A hydrogen atom in a uniform magnetic field of approx. equal to 5 T is treated in a fully quantum mechanical manner. This is done by diagonalising the Hamiltonian for the system in a basis of Sturmian functions. Details of these calculations on the CRAY-1 are presented and results for energy levels and oscillator strengths of transitions in the atom discussed. (orig.)

[en] A classification of the 'b' and 'c' resonances in electron scattering by neon is obtained, which supports previous conjectures made on the basis of the grandparent model. (author)

[en] The oscillator strengths are presented for dipole transitions to high Rydberg states for hydrogen in a magnetic field of 47 kG. The complex spectra can be largely understood in terms of independent, weakly interacting series. (author)

[en] The analytical value of high resolution selected ion monitoring is discussed with particular reference to the use of a small routine gcms instrument. An application of this technique to the assay of pentoxyfylline results in greater than an order of magnitude improvement in detection limits. (Auth.)

[en] It is shown that the quasi-constant of the motion in atomic hydrogen in a uniform magnetic field can be related in a simple way to the asymptotic form of the quantum mechanical wavefunction. The relevance of the quadratic Zeeman effect in evaluations of the oscillator strength for dipole transitions from the ground state of hydrogen to excited states with a single quantum of angular momentum in the direction of the magnetic field is discussed. (U.K.)

[en] A method of calculating highly excited states of hydrogen in uniform magnetic fields of moderate strength (approximately equal to 5 T) is described. Results for Balmer emission lines and an approximate photoabsorption spectrum for Cs are presented. Comment is made on the use of adiabatic approximations and the role of the spin-orbit interaction. (author)

[en] We have analysed the linear Zeeman effect (LZE) for Rydberg states of the H₂ molecule. Three distinct angular momentum coupling schemes are found to be appropriate for different regions of the molecular wavefunction. Using quantum defect theory we have calculated energy level positions and line intensities for n > 5 for photoabsorption from the ¹Σ_g⁺(ν=O,J=O)ground state of H₂. (author)

[en] We consider n = 20 Rydberg states of the hydrogen atom interacting with a nearby metal surface over an atom-surface distance range of 105 nm-530 nm. We show that the traditional quadratic approximation to the potential is insufficient to follow the true potential and one needs to include higher order terms to obtain accurate energies for these Rydberg states. We include terms up to eighth order in the electron-proton distance in the potential and demonstrate by means of basis set calculations that the resulting spectra differ significantly from those obtained in the quadratic approximation. We observe an energy spread of the n = 20 manifold which is roughly twice that given by the quadratic approximation. Observed level repulsions are attributed to z-parity symmetry breaking. We compare our results with those from degenerate perturbation theory. (Author)