Stephen J. Smith

Bio: Stephen J. Smith is an academic researcher from National Institute of Standards and Technology. The author has contributed to research in topics: Ionization & Photoionization. The author has an hindex of 24, co-authored 69 publications receiving 2054 citations. Previous affiliations of Stephen J. Smith include Joint Institute for Nuclear Research & University of Colorado Boulder.

Electron impact excitation of atoms

Abstract: : The experimental and theoretical literature about the electron impact excitation of atoms is reviewed. Theoretical methods ranging from the Bethe and Born approximations to the close coupling approximations are discussed and intercompared. Where possible, on theoretical grounds or through intercomparison, the reliability of the various methods is discussed. A general critique of the optical method of measuring excitation functions is given, with the objective of promoting higher quality future experimental work. A critical study of existing experimental work leads to the conclusion that most workers have ignored important physical and instrumental effects, and it may be presumed that the data in the literature is subject to many unrecognized systematic errors. The literature on hydrogen and helium is discussed critically. The literature on the alkalis, heavy rare gases, mercury, cadmium and zinc is surveyed but the quality of the literature does not support critical review beyond some general comments about the physics of these atoms. (Author)

Extracavity laser band-shape and bandwidth modification

Abstract: A technique for modifying the laser power spectrum by use of an acousto-optic modulator is described. The theory of the power spectrum resulting from frequency modulation by Gaussian noise is reviewed, and several examples of broadened laser power spectra are presented.

Photodetachment Cross Section and the Electron Affinity of Atomic Oxygen

Abstract: Experiments and theory on the continuous absorption of radiation by atomic-oxygen negative ions are described and discussed. The absorption cross section for photon energies not too near threshold is obtained directly from one of the experiments. Theory and experiment are combined to give the cross section in the vicinity of threshold and a precise value of the electron affinity of atomic oxygen. The latter result is EA(O) = 1.465\ifmmode\pm\else\textpm\fi{}0.005 ev. The data are used for computation of the radiative attachment coefficient, and other applications of the experimental results are discussed.

Photodetachment of O - 2

Abstract: The cross section for photodetachment of ${\mathrm{O}}_{2}^{\ensuremath{-}}$ has been measured for the range of photon energies 0.5 to 3.0 ev. No onset energy is discovered in this range but analysis of the data gives an extrapolated threshold at 0.15\ifmmode\pm\else\textpm\fi{}0.05 ev. The curve is found to rise gradually with increasing slope, reaching a value of 2.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}18}$ ${\mathrm{cm}}^{2}$ at 3.0 ev photon energy. Comparison of the data with the predictions of threshold law theory and the results of previous experiments results in an interpretation in terms of assumed potential curves for ${\mathrm{O}}_{2}^{\ensuremath{-}}$.

Relative Measurement of the Photodetachment Cross Section for H

Abstract: The spectral dependence of the photodetachnnent cross section for the negative ion of atomic hydrogen was measured in the range from 4.000 to 13.000 A with approximately 300-A resolution. Measurements were made with twenty-five band pass filters, each measurment taken relative to the value obtained with a control filter at 5280 A. A probable error of about 2% is attached to the relative value obtained for each filter. The results are in significant disagreement with available calculated cross sections. (auth)

X-Ray Fluorescence Yields, Auger, and Coster-Kronig Transition Probabilities

Abstract: The present status of the field of fluorescence yields, radiationless (Auger and Coster-Kronig) and radiative transition probabilities is summarized. Tables of experimental and theoretical results are included, and tables of "best values" of important quantities are presented.

Binding energies in atomic negative ions

Abstract: This article updates a ten‐year‐old review of this subject [J. Chem. Phys. Ref. Data 4, 539 (1975)]. A survey of the electron affinity determinations for the elements up to Z=85 is presented, and based upon these data, a set of recommended electron affinities is established. Recent calculations of atomic electron affinities and the major semiempirical methods are discussed and compared with experiment. The experimental methods which yield electron binding energy data are described and intercompared. Fine structure splittings of these ions and excited state term energies are given.

Inelastic Collisions of Fast Charged Particles with Atoms and Molecules-The Bethe Theory Revisited

Abstract: Since the appearance of the title paper, a number of new developments have occurred which need to be included in that body of material. We present additional remarks and clarifications which supplement and update numerous aspects of the Bethe theory discussed in the earlier paper. We also bring the bibliography up to date. Plasma stopping power, the ${z}^{3}$ effect, and stopping power for particles at extreme relativistic energies are among the new topics included. We make several comments on Fano's earlier review article, Ann. Rev. Nucl. Sci. 13, 1 (1963).

Atomic and molecular electron affinities: photoelectron experiments and theoretical computations.

Abstract: I. Introduction and Scope 231A. Definitions of Atomic Electron Affinities 233B. Definitions of Molecular Electron Affinities 233II. Experimental Photoelectron Electron Affinities 235A. Historical Background 235B. The Photoeffect 236C. Experimental Methods 237D. Time-of-Flight Negative Ion PhotoelectronSpectroscopy239E. Some Thermochemical Uses of ElectronAffinities241F. Layout of Table 10: ExperimentalPhotoelectron Electron Affinities242III. Theoretical Determination of Electron Affinities 242A. Historical Background 2421. Theoretical Predictions of Atomic ElectronAffinities2422. Theoretical Predictions of MolecularElectron Affinities243B. Present Status of Theoretical Electron AffinityPredictions243C. Basis Sets and Theoretical Electron Affinities 244D. Density Functional Theory (DFT) andElectron Affinities245E. Layout of Tables 8 and 9: Theoretical DFTElectron Affinities247F. Details of Density Functional MethodsEmployed in Tables 8 and 9247IV. Discussion and Observations 248A. Statistical Analysis of DFT Results ThroughComparisons to Experiment and OtherTheoretical Methods248B. Theoretical EAs for Species with UnknownExperimental EAs251C. On the Applicability of DFT to Anions and theFuture of DFT EA Predictions251D. Specific Theoretical Successes 251E. Interesting Problems 2521. C

Inelastic collisions of fast charged particles with atoms and molecules the Bethe theory revisited

Abstract: Since the appearance of the title paper, a number of new developments have occurred which need to be included in that body of material. We present additional remarks and clarifications which supplement and update numerous aspects of the Bethe theory discussed in the earlier paper. We also bring the bibliography up to date. Plasma stopping power, the ${z}^{3}$ effect, and stopping power for particles at extreme relativistic energies are among the new topics included. We make several comments on Fano's earlier review article, Ann. Rev. Nucl. Sci. 13, 1 (1963).