Th. M. El Sherbini

Measurement of the Stark Broadening of Atomic Emission Lines in Non–Optically Thin Plasmas by Laser‐Induced Breakdown Spectroscopy

Abstract We propose a new method for determining the Stark broadening of atomic emission lines using laser‐induced breakdown spectroscopy. The method allows the determination of the Stark broadening in non–optically thin plasmas, through the introduction of a correction for self‐absorption. Couples of lines of the same species are considered. If one of the Stark broadenings is known, the determination of the other does not require the measurement of the electron density of the plasma. Examples are given for the application of the proposed method to the measurement of the Stark broadening of several aluminum emission lines (Al I at 308.2 nm, Al I at 394.4 nm, and Al I at 396.2 nm).

Calculation of Xe II line strengths and radiative lifetimes in intermediate coupling

Line strengths for 5s2 5p4 6s−5s2 5p4 6p transition in xenon are calculated in intermediate coupling scheme. The parametric potential method is used in calculating the radial part of the wave functions while the method of least squares fit of energy levels is applied in obtaining the angular part of the wave functions. Lifetimes of the 6p states obtained using these methods show a good agreement with data from electron-impact experiments.

Line strengths and lifetimes for Kr II

Relative line strengths have been calculated for transitions between states of the 4p4 5p and 4p4 5s configurations in Kr II. The wavefunctions are obtained in intermediate coupling, including an effective correction for configuration interaction. Absolute values for the line strengths are determined using the coulomb approximation. Lifetimes for the upper 4p4 5p levels are given together with available experimental results for comparison.

Nanomaterials induced plasma spectroscopy

LIBS of nanosecond pulsed Nd: YAG laser (1064 nm) produced plasma from a set of nanomaterial and bulk targets (ZnO, Fe3O4, Ag2O, TiO2, SiO2 and Al2O3) is investigated at laser fluencies in the range 86 J/cm2 to 2.5 J/cm2. The optical emission spectra is recorded at the gate and time delay of 1 ps after the onset of the plasma in air having a constant spot size of 0.9 mm. Nanoparticle targets revealed salient enhanced spectral emission compared to their bulky counterparts. Atomic spectral lines average and integral radiance tend to decrease exponentially with laser fluence. Yet, plasma parameters measurements indicated unnoticeable variation of relative electron density and temperature. Therefore, self-absorption corrected enhanced spectral emission was plausibly attributed solely to variation in the inherent nanoparticle relative concentrations. Viable explanations were elaborated based on changes in the intrinsic physical properties of the nanomaterial under high power laser irradiation.

Transition probabilities and radiative lifetimes for singly ionized xenon

Transition probabilities between the upper 5p46p configuration and the lower 5p46s of singly ionized xenon are calculated in intermediate coupling. An effective correction for configuration interaction is introduced and its effect is discussed. Lifetimes of the upper states show a better agreement with experimental data than those obtained in LS coupling.

Use of Spectral Lines of a Pure Ti Target for the Spectroscopic Diagnostics of the Laser Induced Plasma in Vacuum

In this paper, we propose a simple method to use the spectral lines which are free from self‐absorption to diagnose the plasma generated from a pure Ti target. The method is based on multiplet spectral lines. Multiplets are very useful in the assessment of self‐absorption, the intensity ratio of their components is usually well known for atoms and ions in LTE and any deviation will indicate the magnitude of the self‐absorption. Ti II spectral lines are developed for measurements of excitation temperature and electron density of plasma generated at different distances from pure titanium target when irradiated by Nd‐YAG 750 mJ in 6 ns FWHM at the fundamental wavelength 1.06μm.

Shapiro step at nonequilibrium conditions

Detailed numerical simulations of intrinsic Josephson junctions of high temperature superconductors under external electromagnetic radiation are performed taking into account a charge imbalance effect. We demonstrate that the charge imbalance is responsible for a slope in the Shapiro step the value of which increases with a nonequilibrium parameter. Coupling between junctions leads to the distribution of the slopes values along the stack. The nonperiodic boundary conditions shift the Shapiro step in IV-characteristics from the canonical position determined by

Evaluation of self-absorption coefficients of aluminum emission lines in laser-induced breakdown spectroscopy measurements

V_{ss}=\hbar f /(2e)

Measurement of electron density utilizing the Hα-line from laser produced plasma in air

, where

Diode laser absorption measurements at the Hα-transition in laser induced plasmas on different targets

f