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1993

Anthony F. Starace Publications

Articles 1 - 7 of 7

Full-Text Articles in Physics

Photodetachment Of The 2P2 (3PE) State Of H-, Ning-Yi Du, Anthony F. Starace, Min-Qi Bao Nov 1993

Photodetachment Of The 2P2 (3PE) State Of H-, Ning-Yi Du, Anthony F. Starace, Min-Qi Bao

Anthony F. Starace Publications

Results of semiempirical, adiabatic hyperspherical calculations are presented for the photodetachment cross section of the process H- 2p2 (3Pe)+γ→H(n=2)+ e- at photon energies in the range from threshold to 0.125 a.u. above. We find the detachment cross section to have a maximum value of 482 Mb at 25.7 meV above threshold, in good agreement with results of close-coupling calculations by Jacobs, Bhatia, and Temkin [Astrophys. J. 242, 1278 (1980)]. In contrast to the close-coupling results, however, we find that the detachment cross section rises by a factor of more ...


Triply Differential (E,2e) Cross Sections For He From Threshold To 50 Ev Above, C. Pan, Anthony F. Starace Oct 1993

Triply Differential (E,2e) Cross Sections For He From Threshold To 50 Ev Above, C. Pan, Anthony F. Starace

Anthony F. Starace Publications

Distorted wave calculations of the triply differential cross sections for electron-impact ionization of He are presented for electrons sharing ≤ 50 eV excess energy (Ex) and having the coplanar, θ12 = π geometry. The results are in good agreement with absolute experimental measurements of T. Rösel et al. [Phys. Rev. A 46 (1992) 2539-2552] and of A. J. Murray, M. B. Woolf, and F. H. Read [J. Phys. B 25 (1992) 3021-3036]. For final state electrons sharing 2 eV excess energy equally, many-body perturbation theory corrections to the authors' first order (e,2e) triply differential cross sections [Phys. Rev. A ...


Electric-Field Effects On H- Photodetachment With Excitation Of H(N=2), Ning-Yi Du, Ilya I. Fabrikant, Anthony F. Starace Oct 1993

Electric-Field Effects On H- Photodetachment With Excitation Of H(N=2), Ning-Yi Du, Ilya I. Fabrikant, Anthony F. Starace

Anthony F. Starace Publications

A theory of the photodetachment of hydrogen negative ions in an external static electric field with the production of hydrogen in excited states is developed. We use a combination of the frame-transformation theory and the Green’s-function method. The cross section in nonzero fields is expressed in terms of the photodetachment matrix elements for zero field. The latter are calculated using the adiabatic hyperspherical representation. For energies close to the threshold we use a smooth extrapolation of the zero-field photodetachment matrix elements down to threshold taking care to enforce the proper threshold behavior of cross sections for nonzero fields. The ...


Resonant Two-Color Detachment Of H- With Excitation Of H(N=2), Ning-Yi Du, Anthony F. Starace, N.A. Cherepkov Sep 1993

Resonant Two-Color Detachment Of H- With Excitation Of H(N=2), Ning-Yi Du, Anthony F. Starace, N.A. Cherepkov

Anthony F. Starace Publications

The cross sections for resonant two-color, two-photon detachment of H- with excitation of the degenerate H(2s) and H(2p) levels are calculated within a semiempirical adiabatic hyperspherical representation. The first photon, with energy ω1=0.4017 a.u., is resonant with the well-known Feshback 1P0 resonance below the H(n=2) threshold. The second photon, with energy ω2≥0.126 05 a.u., scans the energy region above the H(n=2) threshold over which long-range dipole-field-induced cross-section oscillations are predicted to occur. Such Gailitis-Damburg oscillations have not yet been observed experimentally. Results ...


Short-Pulse Detachment Of H- In The Presence Of A Static Electric Field, Qiaoling Wang, Anthony F. Starace Sep 1993

Short-Pulse Detachment Of H- In The Presence Of A Static Electric Field, Qiaoling Wang, Anthony F. Starace

Anthony F. Starace Publications

Quantum interference effects occurring in photodetachment of H- in the presence of a uniform, static electric field are shown theoretically to be controllable through use of short laser pulses having characteristic times comparable to photodetached electron reflection times. In particular, calculated cross sections for single-photon detachment by two laser pulses that are delayed and phase shifted relative to one another are shown to oscillate as a function of the relative phases of the laser pulses at fixed photodetached electron energy.


Angular Distributions For Near-Threshold (E,2E) Processes For Li And Mg, Cheng Pan, Anthony F. Starace Mar 1993

Angular Distributions For Near-Threshold (E,2E) Processes For Li And Mg, Cheng Pan, Anthony F. Starace

Anthony F. Starace Publications

Distorted-wave calculations of the triply differential cross sections for electron-impact ionization of Li and Mg are presented for the coplanar, θ12=π geometry in which the final-state electrons share 2 eV of excess energy equally. Our theoretical approach, described in detail elsewhere [C. Pan and A. F. Starace, Phys. Rev. A 45, 4588 (1992)], employs a partial-wave expansion of initial- and final-state wave functions, treats direct and exchange interactions of initial and final electrons with the target core, and treats the final-state interaction between the two continuum electrons by a screening potential. Li and Mg targets are found to ...


Relative Photoionization And Photodetachment Cross Sections For Particular Fine-Structure Transitions With Application To Cl 3S-Subshell Photoionization, Cheng Pan, Anthony F. Starace Jan 1993

Relative Photoionization And Photodetachment Cross Sections For Particular Fine-Structure Transitions With Application To Cl 3S-Subshell Photoionization, Cheng Pan, Anthony F. Starace

Anthony F. Starace Publications

The relative photoionization cross section for starting from a particular fine-structure level of the initial state of an atomic system and leading to a particular fine-structure level of the residual ion is presented for the case of atomic systems having one open subshell using a simple theoretical model in which emphasis is placed on the analysis of geometrical effects. This model parametrizes photoionization cross sections in terms of LS-dependent, single-configuration dynamical amplitudes, unlike previous treatments which assume LS-independent transition amplitudes from the start. In special cases our general formulas are shown to reduce to those of previous workers ...