The effect of correlation on the ${\mathit{g}}_{\mathit{J}}$ factors of ground-state and some metastable 2s- and 2p-row atoms is evaluated from experimental data and theoretical values calculated within the Hartree-Fock scheme. By taking the accurate experimental ${\mathit{g}}_{\mathit{J}}$${(}^4$${\mathit{S}}_{3/2}$) values of atomic nitrogen as reference, the effect is seen to amount to -1.0 ppm per unpaired 2l electron. A configuration-interaction calculation for ${\mathit{g}}_{\mathit{J}}$(N${;}^4$${\mathit{S}}_{3/2}$) yields a value that agrees with experiment to within 0.24 ppm. This also shows that the effect of correlation on ${\mathit{g}}_{\mathit{J}}$(N${;}^4$${\mathit{S}}_{3/2}$) is mainly due to core polarization and amounts to -0.94 ppm per polarizing 2p electron.

The stopping number of hydrogen atoms calculated with Bethe’s theory in the first Born approximation is tabulated. A comparison is made with the asymptotic approximation and with a model based on the harmonic oscillator.

I predict that the differential cross sections for elastic and inelastic scattering of ${\mathrm{H}}^{\mathrm{-}}$ with atoms will exhibit sharp minima. These minima result from the cancellation between the contributions to the cross section by the positively charged nucleus and the two negatively charged electrons of ${\mathrm{H}}^{\mathrm{-}}$. The location for such minima is predicted based on a simple first Born approximation, but should be correct at least for intermediate to high impact energies.

We analyze the exact ionization spectrum for ion-atom collisions with potentials of zero range in one and three dimensions. We find evidence for intrinsic three-body scattering effects in the continuum in the region of ‘‘v/2 electrons’’ as well as at very high speeds. The relation of the position of the v/2 ‘‘hump’’ to the motion of the improper saddle for the δ potential is discussed.

The spectral moments S(k) and L(k) of the dipole oscillator strength distribution of water have been calculated in the random-phase approximation as a function of molecular geometry. Several of the moments vary quite strongly with the O-H bond distance, while the dependence on bond angle is much less pronounced. In particular, the mean excitation energy is seen to change strongly with ${\mathit{R}}_{\mathrm{OH}}$, being 72.92 eV when calculated at the molecular equilibrium geometry, and 71.61 eV in the vibrationally averaged ground state. Vibrationally averaged values of S(k), -6≤k≤1, are also reported along with the mean excitation energy for straggling, ${\mathit{I}}_1$.

We establish a connection between the unitary phase operator recently introduced by Pegg and Barnett [Europhys. Lett. 6, 483 (1988)] with a useful representation due to Bialynicki-Birula, which allows for powerful semiclassical expansions.

It is found that inclusion of the self-steepening contribution in the generalized nonlinear Schrödinger equation allows for the possibility of truly hysteretic bistable solitary-wave behavior, characterized by the appearance of an N-shaped energy curve, for nonlinear functions f(I) that do not support bistability when self-steepening is neglected. This finding is discussed in the framework of one-dimensional optical pulse propagation.

The motion of a laser pulse with a specified asymptotic form, traversing a localized static magnetic field, is studied for an atomic J=0 ground-state to a J=1 excited-state transition. It appears that for this specific dispersive medium, consisting of the atoms in the magnetic field, an analytic expression can be given for the velocity and phase of a single-soliton laser pulse.

Through use of the notation of thermofield dynamics, an exact solution of a class of master equations describing coupled nonlinear oscillators is presented.

Barut and Dowling [Phys. Rev. A 41, 2284 (1990)] have raised questions concerning the ‘‘illegal use’’ of superposition in the neoclassical radiation theory of Crisp and Jaynes [Phys. Rev. 179, 1253 (1969)]. They also continue to use an expansion for their wave function that has been questioned as to its validity and interpretations [Bialynicki-Birula, Phys. Rev. A 34, 3500 (1986)]. Both of these points will be discussed in this Comment.

The remarks in the preceding Comment by M. D. Crisp [Phys. Rev. A 43, 4058 (1991)] do not really apply to self-field quantum electrodynamics.

The atomic quantum-defect theory proposed by Kostelecký and Nieto [Phys. Rev. A 32, 3243 (1985)] is proven to be basically identical to the earlier published quantum-defect orbital formalism.

The preceding paper, by Martin and Barrientos [Phys. Rev. A 43, 4061 (1991)], comments on our supersymmetry-inspired model of atomic physics. We relate this to other Comments [Rau, Phys. Rev. Lett. 56, 95 (1986) and Goodfriend, Phys. Rev. A 41, 1730 (1990)] and point out that, although the mathematics and physics of the 1974 Simons model [J. Chem. Phys. 60, 645 (1974)] is similar to ours, it is not identical. This is elucidated by explicitly comparing our symmetry-based approach to the more phenomenological approach of Martin and Barrientos.

In a recent paper Stoneman, Thomson, and Gallagher [Phys. Rev. A 37, 1527 (1988)] studied the excitation of potassium Rydberg atoms in microwave fields for a few values of the initial S-state principal quantum number. In one case the measured excitation probability as a function of microwave amplitude showed a rather broad feature that was explained in terms of level crossings between quasienergy states. The details of a crucial ingredient of this explanation, namely, a broadening mechanism, were, however, left unexplained.

High-resolution 0° Auger spectroscopy has been used to study the Ne LMM and LMN Auger emission. The doubly excited states in B-like Ne are produced via nonresonant transfer and excitation (NTE) in collisions of 15 to 60-keV/amu ${\mathrm{Ne}}^{6+}$ incident on He. Line assignments are given for Auger transitions observed in the energy range between 20 and 100 eV, and capture into a triplet state is observed. The relative cross sections for these rates show a broad (>300 keV full width at half maximum) asymmetrical shape as a function of projectile energy, characteristic of the NTE process.

We report experimental angular differential cross sections for one-electron capture in ${\mathrm{Ar}}^{6+}$-He collisions at very low energies (1.6–13 eV/u). The cross sections show an expectedly high population of core-excited states of ${\mathrm{Ar}}^{5+}$. An alternative mechanism for enhanced capture excitation through configuration interaction is proposed.

A general analytic theory of spontaneous and stimulated rotational Raman scattering is presented. This analytic description incorporates arbitrary polarization, time dependence, phase matching, and parametric coupling of the pump, Stokes, and anti-Stokes fields and the degeneracy of the rotational states. The analytic expressions for the time-dependent Stokes and anti-Stokes fields provide valuable physical insight into the dynamics of spontaneous and stimulated rotational Raman scattering.

We observed single-shot spatial interference from two independent pulsed-light sources using stimulated Raman scattering (SRS) in the transient, macroscopic-field regime. By measuring the phase distribution of the Stokes field and the fourth-order spatial correlation function, we verified that the Stokes field obeys thermallike statistics in the unsaturated SRS gain regime. This reflects the properties of the underlying quantum noise in the vacuum field and scattering medium. A transition from thermallike to laserlike statistics occurs when the gain becomes saturated.