A configuration interaction study of the spin dipole-dipole parameters for formaldehyde and methylene

The electron spin dipole-dipole contribution to the zero field splitting has been evaluated for the ³A₂ (n → π*) and ³A₁ (π → π*) states of formaldehyde using a CI wave function constructed from contracted Gaussian-lobe functions. The values D = 0.539 cm^?1 and E = 0.031 cm^?1 were obtained for the ³A₂(n → π*) state and D = ?0.588 cm^?1 and E = 0.058 cm^?1 were obtained for the ³A₁ (π → π*) state using the CI wave function constructed from SCF orbitals of the respective parent configurations. An analysis of the effect of CI on the parameters is given for the ³A₂ (n n → π*) state of formaldehyde and the ³B₁ ground state of methylene. Numerical results are given which show that internally consistent self-consistent field orbitals (ICSCF ) are superior to canonical SCF orbitals as a starting point for a CI calculation. Our CI wave function for the ¹A₁ ground state gave an energy of ?114.13658 hartrees which is significantly lower than any previously reported energy calculation. This wave function gives a dipole moment of 2.22 Debye (C⁺O^?) in good agreement with the experimental value of 2.33 ± 0.02 Debye.     

A high power N2 laser using water filled strip lines

A fast Blümlein circuit with a water strip line having an impedance of Z=0.078 is used to excite a TE high power nitrogen laser at =337 nm. A pseudospark switch works as a high power switch. The laser operates without any preionization and delivers an energy of 15 mJ per pulse (7.5 ns FWHM) at 10 kPa nitrogen pressure. The shot to shot reproducibility is better than 5%.     

Mössbauer effect in187rhenium

The Mössbauer effect of the 134 keV transition in¹⁸⁷Re has been investigated in order to determine the Debye-Waller factors of rhenium in different environments. The Debye temperatures of Re (Re) and Re (W) were determined to be (9 K)=(291±10) K and=(298±5) K, respectively. These data are compared with results obtained by other methods.     

Nondipolar electron angular distributions from fixed-in-space molecules

The first indication of nondipole effects in the azimuthal dependence of photoelectron angular distributions emitted from fixed-in-space molecules is demonstrated in N (2). Comparison of the results with angular distributions observed for randomly oriented molecules and theoretical derivations for the nondipole correction first order in photon momentum suggests that higher orders will be needed to describe distributions measured in the molecular frame.     

Tchebycheff-derivative approximations to photoabsorption cross sections in atoms and ions

Spectral moments and Tchebycheff's inequalities are employed in the construction of continuous, convergent approximations to photoabsorption and ionization cross sections in atoms and ions.     

Lasing in an e beam pumped Ar-N2-mixture at 406 nm

An Ar−N₂-mixture was excited by a relativistic e-beam in a longitudinal pumping geometry. Lasing is observed for the trasitions from the N₂(C) to the lower three vibrational states of N₂(B) at λ=337, 358, and 380 nm and for the first time also to the fourth vibrational state at λ=406 nm.     

Potential curves of the rare gas alkali ions

The first excited states of the rare gas alkali ions have been calculated using Hellmanntype model potentials. The predicted decay energies agree with the results of a recent measurement within 2%.     

The level shift operator and its effect on line shapes in vibronically perturbed spectra

This paper discusses the role of the level shift operator in vibronically mixed molecular resonances. The effect of this operator on the shapes of resonances is particularly important when the resonances contain resolved structure.     

Computational identification of interface delaminations in layered composites based on surface measurements

One of the main contemporary challenges facing engineering sciences is how to identify the actual state of internal defects, their self-organized criticality, interaction, and thus influence on the overall strength and durability of a system. In this study we address one aspect in the panoply of problems emerging in this context, namely: how to identify a single delamination in a layered composite specimen performing measurements only on the surface. In rigor terms the answer to this question relates to the answer to the question of how to solve the nonlinear semi-inverse problem of the mathematical programming emerging from the minimization of an associated Kohn–Vogelius functional with respect to some set of design variables parameterizing the delamination region. Clearly, one methodological way to approach the solution is to use some classical, gradient-based, nonlinear programming technique, like SQP. One should not forget, however, that the identification problems of this class are per se ill-posed, nonsmooth, and highly sensitive to the initial boundary data. Three bottlenecks occur that cannot be trivially circumvented when the shape of the delamination region, its characteristic dimensions, and position are preliminarily unknown (or highly uncertain). Based on an appropriate split of the governing Kohn–Vogelius functional we succeed here in transforming the ill-posed local inverse problem into a coupled system of elliptic well-posed Euler–Lagrange equations and to derive a direct smooth iterative strategy for its numerical solution. The strategy leads to a semiempirical reconstruction method for finding isolated interlaminar cavities from the measurement of the displacement field performed on the surface of the specimen.