William S. Bickel

Stokes vectors, Mueller matrices, and polarized scattered light

The complete characterization of scattered light is described in the context of Stokes vectors and Mueller matrices which highly motivates the measuring procedures. The most general form of the scattering matrix coupled with polarizers and quarter wave plates elegantly demonstrates the physical relationship among the matrix elements and polarization measurements.

Scattering from a small sphere near a surface

We examine four theories that predict the scattered radiation from a system composed of a small sphere and a plane and show that in the far field the scattering amplitude components predicted by these theories are essentially the same. We express the scattering intensities in Mueller matrix representation and examine the far-field Mueller matrix as a function of various parameters.

Transitions and level lifetimes in Ne II, III, Ar II, III, Kr II, III and Xe II☆

Abstract Beam-foil spectra of neon, argon, krypton, and xenon have been recorded photographically with a fast spectrograph. The particle energies ranged from 150 to 750 keV. Transitions in Ne II, III; Ar II, III; Kr II, III; and Xe II have been identified. In addition, new multiples were identified in Ne II and Xe II and a number of unidentified lines were observed in neon, argon, and krypton. Characteristic intensity decays of over 170 lines were measured, giving the mean lives of ≈ 80 levels, with an estimated error of 30 per cent. Tabulation of energy levels with similar electron configurations in neon, argon, krypton, and xenon shows a definite progression to larger mean lives as the nuclear change increases.

Beam-Foil Spectra of Boron 450–5000 Å*

Electronic transitions in B i–B iv have been studied with the beam-foil technique. Over 100 spectral lines were observed between 450 and 5000 A. Only half of the lines could be assigned to earlier known boron transitions. Classifications are given for several of the new lines. Mean lives of 33 excited levels in B i–B iv were measured. In most cases the results are in good agreement with theory.

Mean Lives of Excited Levels in O i–O vi*

Oxygen spectra between 450 and 2200 A were studied with the beam-foil technique. Mean lives of over 50 excited levels in O i–O vi were measured.

Light scattering Mueller matrix for a surface contaminated by a single particle in the Rayleigh limit

A ray-tracing model was used to derive the light scattering Mueller matrix element curves for a dipole near a perfect surface as a function of incident angle, scattering angle, and surface refractive index. This system represents a fundamental system composed of a perfect plane surface and a perfect (Rayleigh) scatterer.

Polarized light-scattering matrix elements for select perfect and perturbed optical surfaces

The angular distribution of scattered light depends on the electromagnetic properties (refractive index, absorptivity), the geometrical properties (size, shape, and distribution) of the scatterer(s), as well as the polarization and illumination angle of the incident light. To study the total information content, we measured the entire experimental sixteen-element Mueller scattering matrix for a smooth reflecting aluminum surface illuminated with lambda = 4416-A light at various angles of incidence alpha. In comparison, we also measured the scattering matrix for a degraded surface of identical material. This paper discusses the experimental procedure and compares the scattering results obtained from these two types of surface.

Single fiber light scattering matrix: an experimental determination

The entire light scattering matrix is experimentally determined for two fused silica cylinders illuminated at normal incidence (lambda441.6 nm). Radii of 0.960 +/- 0.002 and 3.091 +/- 0.003 microm are determined by comparison with Mie theory indicating that micron-sized fiber radii can be determined to within a few nanometers by polarized light scattering techniques. The single fiber provides a good calibration source for polarization nephalometers, being free from problems inherent with spheres in solution. The fiber is a well-known geometry which is amenable to perturbation toward irregular shapes, and as such it provides the starting point for studying scattering from irregular particles.

Beam-Foil Studies of Nitrogen*

Beam-foil spectra of nitrogen were obtained for particle energies between 0.25 and 2.0 MeV in a wavelength range between 1050 and 3000 A and up to 5.5 MeV between 2000 and 5000 A. Most of the spectral lines are ascribed to known transitions in N i–vi. Many Si i–vi transitions could also be identified in the spectrum of the mass-28 beam. Twenty-five decay times of nitrogen were measured. In some cases, the experimental mean lives differ by factors as large as 4 from theoretical values.

Mean lives of some excited levels of Li I and Li II.

A beam of 7Li+ ions accelerated to 56 keV by an electromagnetic isotope separator was directed through a thin carbon foil. The emergent ions were in various charge and excitation states, from which 26 spectral lines of Li i and Li ii were identified. The decay times of eight stronger lines were measured in order to determine the mean lives of upper levels involved in the decays.