Daniel E. Kelleher

Stark broadening of visible neutral helium lines in a plasma

Abstract Side-on observations of the visible spectrum emitted by a helium plasma generated in a wall-stabilized arc are reported. Electron densities range from 0.2 to 1.3 × 10 22 m -3 and electron temperatures vary from 10,000 to 20,000 K. Most of the seventeen measured lines are “isolated” at the conditions of the experiment. Here, “isolated” refers to quantum levels which are non-degenerate even in the presence of perturbing fields. Electron densities derived from the Stark-widths of the isolated lines agree to within 15% of the values determined from Hβ and from the quasi-degenerate He(I) lines at 4471 and 4921 A. Similar agreement is observed for the static-ion Stark broadening parameters. However, at the conditions of this experiment, the static-ion approximation is not valid near the center of some of the isolated lines. The observation of ion-dynamic effects in neutral isolated lines is reported here for the first time. In the isolated lines, the measured ion-dynamic effects are reasonably consistent with calculations based on an adiabatic “unified” theory for the ion perturbers. A simple parametric expression closely approximates the ion-dynamic contribution to the half-width of isolated lines. Hydrogenic (non-isolated) neutral helium lines exhibit a large discrepancy with theoretical profiles near the line center, where ion-dynamic effects are important.

Critically Evaluated Atomic Transition Probabilities for Sulfur S I – S XV

Atomic transition probabilities for about 6400 allowed and forbidden lines of S I – S XV are tabulated based on a critical evaluation of recent literature sources. The transition probabilities were obtained mainly from recent sophisticated calculations carried out with complex computer codes. These tables provide data of interest for astronomical as well as laboratory plasmas. They will also be useful for the diagnostics of plasmas encountered in fusion energy research.

Atomic Transition Probabilities of Sodium and Magnesium. A Critical Compilation

This compilation is the first in a series of updates to a critical compilation published in 1969 [W. L. Wiese, M. W. Smith, and B. M. Miles, Atomic Transition Probabilities, Vol. II: Sodium through Calcium, NSRDS-NBS Vol. 2 (U.S. GPO, Washington, D.C., 1969)]. Atomic transition probabilities have been critically evaluated and compiled for about 11 400 spectral lines of sodium and magnesium (nuclear charge Z=11–12, respectively). The cited values and their estimated uncertainties are based on our consideration of all available theoretical and experimental literature sources. All ionization stages (except for hydrogenic) are covered, and the data are presented in separate tables for each atom and ion. Separate listings are given for “allowed” (electric dipole) transitions, on the one hand, and for “forbidden” (magnetic dipole plus electric and magnetic quadrupole) transitions, on the other. In each spectrum, lines are grouped into multiplets which are arranged in order of ascending lower and upper-level ene...

Atomic Transition Probabilities of Silicon. A Critical Compilation

This compilation is the third in a series of updates to a critical compilation published in 1969 by Wiese et al. [Atomic Transition Probabilities, Vol. II: Sodium through Calcium, NSRDS-NBS Vol. 22 (U.S. GPO, Washington, D.C., 1969)]. Atomic transition probabilities have been critically evaluated and compiled for about 5800 spectral lines of silicon (nuclear charge Z = 14 ). The cited values and their estimated uncertainties are based on our consideration of all available theoretical and experimental literature sources. All ionization stages (except for hydrogenic) are covered, and the data are presented in separate tables for each atom and ion. Separate listings are given for “allowed” (electric dipole) and “forbidden” (magnetic dipole plus electric and magnetic quadrupole) transitions. In each spectrum, lines are grouped into multiplets which are arranged in order of ascending lower and upper level energies, respectively. For each line, the emission transition probability A k i , the line strength S , a...

Advances in plasma broadening of atomic hydrogen

The Stark broadening tables for hydrogen Lyman, Balmer and Paschen lines published in the early seventies give accurate results for the widths of the β lines down to relatively low electron densities, and for the far line wings in general. However, the half-widths of the α lines can be in error by as much as a factor of 30, particularly at intermediate densities. Modern theoretical methods are capable of producing accurate values over the entire density range. Recent developments in the Stark broadening of non-hydrogenic species are also considered.

Atomic Transition Probabilities of Aluminum. A Critical Compilation

This compilation is the second in a series of updates to Atomic Transition Probabilities, Sodium through Calcium, published in 1969 by Wiese et al. [Atomic Transition Probabilities, Vol. II, Vol. II: Sodium through Calcium, NSROS-NBS Vol. 2 (U.S. GPO, Washington, D.C., 1969)]. Atomic transition probabilities have been critically evaluated and compiled for about 5000 spectral lines of aluminum (nuclear charge Z = 13 ). The cited values and their estimated uncertainties are based on our consideration of all available theoretical and experimental literature sources. All ionization stages (except for hydrogenic) are covered, and the data are presented in separate tables for each atom and ion. Separate listings are given for “allowed” (electric dipole) and “forbidden” (magnetic dipole plus electric and magnetic quadrupole) transitions. In each spectrum, lines are grouped into multiplets which are arranged in order of ascending lower- and upper-level energies, respectively. For each line, the emission transitio...

Determination of trace elements in zinc by isotope dilution spark source mass spectrometry

Abstract The applicability of the isotope dilution technique in spark source mass spectrometry has been investigated for the determination of Pb, Cu, Cd, Ag, Tl, and Sn in zinc metal. In the procedure developed, a solution of the zinc is spiked with known amounts of stable isotopes of the elements to be determined, and the elements are electrodeposited onto gold wires that subsequently serve as electrodes for the mass spectrographic isotopic analysis. Chemical operations, including isothermal distillation of reagents, dissolution of the zinc, and the electro-deposition step are conducted in a closed system to minimize contamination. The results of the analysis of two NBS zinc standard reference materials include determinations ranging from 11 ppm (11 μg g ) for Pb to as low as 0.02 ppm (20 ng g ) for Sn. It is concluded that this method is of general utility for simultaneous multi-element trace analysis and is especially applicable in providing much needed standardization in spark source mass spectrometry.

Transition Probabilities for Prominent Ar i Lines in the Near Infrared

Relative transition probabilities of 81 infrared Ar i lines in the wavelength range from 9000–24 000 A have been measured with a wall-stabilized arc operating in argon at atmospheric pressure. The large majority of the lines from the 4p–5s and 4p–3d transition arrays has been observed and the measurements are consistent with the J-file-sum rule. The data have been normalized to an absolute scale by utilizing the results of other recent arc and lifetime experiments.

Four-wave sum mixing in beryllium around hydrogen Lyman-α

Radiation was generated between 1210 and 1230 A by four-wave sum mixing in beryllium vapor where the 2s(2)(1)S-2s3d(1)D transition was two-photon resonant. Results indicate that beryllium will be an efficient nonlinear medium in this spectral region with improvements to the stability of the furnace to allow phase matching and operation at higher pressures.

Atomic Spectral Tables for the Chandra X-Ray Observatory. Part I S VIII–S XIV

Tables of critically compiled wavelengths, energy levels, line classifications, and transition probabilities are given for spectra of ionized sulfur (S VIII–S XIV) in the region 21–170 A. These tables provide data of interest for the Emission Line Project in support of the analysis of astronomical data from the Chandra X-Ray Observatory. They will also be useful for the diagnostics of plasmas encountered in fusion energy research. The transition probabilities were obtained mainly from recent sophisticated calculations carried out with complex computer codes.