A.G. Trigueiros

Determination of plasma temperature by a semi-empirical method

Doppler or Stark line broadening effects are generally used to determinate plasma temperature. These methods are difficult to apply to spectra of highly ionized atoms due to the short wavelengths involved. It is not at all easy to achieve sufficient wavelength resolution in this spectral range. In this case, a spectroscopic technique based on the relative intensities of lines must be used to measure the electron temperature in a plasma. However the relation of the measure of relative line intensity and the plasma electron temperature is complex and a number of issues must be examined for the diagnostic. In simple cases, only a two levels system need be considered. Here we introduce a semi-empirical method to determine the plasma temperature that takes into account multiple levels structure. In the theoretical model we consider a local thermodynamic equilibrium(LTE). The greatest difficult in the determination of plasma temperature using a multiple levels approach is overcome by calculating the transition probabilities in terms of the oscillator strength parameters. To check the method we calculated the oscillator strengths for the Cu I using a multi-configurational Hartree-Fock relativistic (HFR) approach. The electrostatic parameters were optimized by a least-squares procedure, in order to obtain the best fitting to the experimental energy levels. This method produces gf- values that are in better agreement with their experimental values than the produced by the ab initio calculation. The temperature obtained was 5739.3 K, what is compatible with direct measurements made for cupper DC discharge.

Weighted oscillator strengths and lifetimes for the SVII spectrum

The weighted oscillator strengths (gf) and the lifetimes presented in this work were carried out in a multiconfiguration Hartree-Fock relativistic approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure, in order to improve the adjustment to experimental energy levels. This method produces gf-values that are in better agreement with intensity observations and lifetime values that are closer to the experimental ones. In this work, we presented all the experimentally known electric dipole S VII spectral lines.

Weighted oscillator strengths and lifetimes for the S IX and S X spectra

Abstract The weighted oscillator strengths ( gf ) and the lifetimes presented in this work were carried out in a multi configuration Hartree–Fock relativistic (HFR) approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure, in order to improve the adjustment to experimental energy levels. This method produces gf -values that are in better agreement with intensity observations and lifetime values that are closer to the experimental ones. In this work, we presented all the experimentally known electric dipole S IX and S X spectral lines.

A compilation of wavelengths and energy levels for the spectrum of neutral rubidium (RbI)

Abstract We are presenting a complete list of wavelengths for all classified lines of Rbxa0I. The data are based mainly on the observations and analysis of this spectrum by many authors. The tabulated data include 615 observed lines in the spectral range 103– 27,905 A , classified as transitions among 22 even-parity and 414 odd-parity levels. Vacuum wavelengths are given for all the lines, and wavelengths in air are also included for the region above 2000 A . We also present the results of the doppler-free two-photon absorption spectrum for the transition n 2 S←5 2 S and n 2 D←5 2 S of atomic rubidium.

Wavelengths, Energy Levels, Lifetimes, and Weighted Oscillator Strengths for the S VIII Spectrum

The weighted oscillator strengths (gf) and lifetimes for S VIII presented in this work were obtained by a multiconfigurational Hartree-Fock relativistic approach. In this calculation, the electrostatic energy parameters were optimized by a least-squares procedure in order to improve the adjustment to experimental energy levels. The values for gf and lifetimes were then calculated on the basis of these adjusted parameters. New classifications are proposed for energy levels belonging to the 4s and 4d configurations and lines related to them.

The study of 3s3p4 configuration in the P-Sequence, Co XIII - Ni XIV, by laser-produced plasmas

Wavelengths from radiation of plasmas produced by a Nd:YAG/glass laser focused on target of Co and Ni have been recorded photographically in the region 240-600 A with a 3m normal incidence spectrograph. For this sequence (Co XIII and Ni XIV) we have identified 13 new lines belonging to the array 3s23p3-3s3p4 and derived 7 new levels for the 3s3p4 configuration. The classification was established by comparison of the relative intensities for the lines along the isoelectronic sequence, extrapolation, and Hartree-Fock calculation.