K J Ross

The ejected-electron spectrum of Li I autoionising levels excited by low-energy electron impact on lithium vapour

The ejected-electron spectrum of lithium vapour has been observed at 75 degrees with respect to an incident electron beam of 80 eV, 200 eV and 500 eV kinetic energy. A total of 39 autoionising levels of Li I are observed in the energy range 56 eV to 65 eV. Comparison is made with experimental and theoretical data.

Generalized oscillator strengths in the electron impact spectra of rubidium and caesium

Studies of generalized oscillator strengths as a function of incident electron kinetic energy within the range 33·5-100·5 eV have been made for rubidium and caesium using a crossed-beam high-resolution electron energy-loss spectrometer. Absolute generalized oscillator strengths have been derived by normalizing the resonance transition to the optical oscillator strength. For rubidium the reduced matrix elements (5 2Sparallelr2parallel6 2S) and (5 2Sparallelr2parallel7 2S) were found to be 44 A.U. ±25% and 15 A.U. ±40%, respectively, and the transition probabilities A(4 2D -> 5 2S) and A(5 2D -> 5 2S) found to be 204 s-1 ±10% and less than 24 s-1, respectively. For caesium the reduced matrix element (6 2Sparallelr2parallel7 2S) was found to be 57 A.U. ±20%, and the transition probabilities A(5 2D -> 6 2S), A(6 2D -> 6 2S) and A(7 2D -> 6 2S) were found to be 49 s-1 ±10%, 94 s-1 ±20% and 80 s-1 ±40%, respectively.

High-resolution ejected-electron spectra of K I and K II autoionising levels excited by low-energy electron impact on potassium vapour

The ejected-electron spectrum of potassium vapour has been observed at 50 degrees and 75 degrees with respect to an incident-electron beam of 30 to 400 eV incident energy. Ejected-electron energies are in the range 4 to 21.5 eV. A total of 84 autoionising states of K I are reported, of which 49 have been identified by comparison with ultraviolet absorption data. Some of the remaining levels are assigned tentatively using available theoretical data. In addition, three states belonging to the K II autoionisation spectrum are identified.

High-resolution ejected-electron spectrum of magnesium autoionising levels following two-electron excitation by low-energy electron impact

The ejected-electron spectrum of magnesium vapour following autoionisation of two-electron excited states of the type 1s22s22p63pnl is presented for the first time. Ejected electrons were energy analysed at 75 degrees to the direction of an incident electron beam of energy 17 to 500 eV. 46 lines are reported in the ejected-electron energy range 0.5 eV to 4.5 eV, of which 40 have been assigned to eight series. Comparisons are made with ultraviolet observations and theoretical calculations.

A study of the 4p-excited autoionization resonances in Sr by measurement of the angular correlation between the photoejected electrons and polarized fluorescent photons

For five autoionization resonances of Sr in the 4p excitation region, we have determined the ratios of five amplitudes and one phase difference for the photo-ejected electron waves which leave the ion in the excited states. The technique employed is a combination of conventional angle-resolved photoelectron spectroscopy, and angular correlation measurements between photoejected electrons and polarized fluorescent photons. We discuss how the ratios of the dipole amplitudes are related to the spectroscopic descriptions of the resonances studied.

The ejected-electron spectrum of thallium vapour autoionising levels excited by low-energy electron impact

The ejected-electron spectrum of thallium vapour has been observed at 75 degrees with respect to an incident electron beam of 15-500 eV kinetic energy. A total of 92 ejected-electron lines corresponding to autoionisation processes in Tl I are reported. Hartree-Fock calculations together with data from photoabsorption measurements have been used to assign the observed lines where possible.

High-resolution ejected-electron spectrum of caesium vapour autoionising levels excited by 30 to 400 eV electrons

The ejected-electron spectrum of caesium vapour has been observed at 75 degrees with respect to an incident electron beam of 30 to 400 eV incident energy. A total of 63 autoionising states, between 8.3 and 13.4 eV ejected-electron energy, are reported. Of the observed states, 37 have been identified by comparison with ultraviolet absorption data.

Angular correlation measurement between the photo-excited autoionized electron and subsequent polarized fluorescent photon at an autoionization resonance of Sr

We demonstrate that the technique of measuring the angular correlation between the photoejected electron and polarized fluorescent photon can be used to determine all the photoionization parameters for the relativistic case. Applying this technique to an autoionization resonance of atomic Sr, values were obtained for the ratios of the three dipole amplitudes and the two phase differences.

A simple resistively heated vapour beam oven with an interchangeable crucible

Abstract A description is given of a resistively heated oven which is suitable for the production of vapour beams requiring source temperatures up to 1000°C. The main features of the oven are the simplicity of construction and the ease with which the crucible holding the charge can be interchanged.

The ejected-electron spectrum of cadmium vapour autoionizing levels excited by 15 to 400 eV electrons

The ejected-electron spectrum of cadmium vapour has been observed at angles up to 110 degrees with respect to an incident electron beam of kinetic energy 15 to 400 eV under high-resolution conditions. Comparisons are made with earlier ejected-electron spectra, ultraviolet absorption measurements and theoretical calculations. The spectrum is found to contain some lines which are not observed in optical studies. Angular distributions are found to exhibit pronounced maxima and minima in a number of cases.