A dynamic nuclear magnetic resonance study of 1,3-intramolecular shifts in pentacarbonyl-chromium(O) and -tungsten(O) complexes of β-2,4,6-trimethyl-1,3,5-trithian, 1,3,5-trithian, 1,3-dithian and 2-methyl-1,3-dithian: the x-ray crystal structure of [W(CO)5{SCH(Me)SCH(Me)SCH(Me)}]

Variable temperature ¹H NMR spectroscopy has been used in the study of 1,3-intramolecular shifts of the M(CO)₅ moiety in complexes of the general formula [M(CO)₅L], (M = Cr or w), L = $\text{SCH}{}_2\text{SCH}{}_2\text{SC}$H₂, $\text{SCH}{}_2\text{SCH}{}_2\text{CH}{}_2\text{C}$H₂ and $\text{SCH(Me)SCH}{}_2\text{CH}{}_2\text{C}$H₂. For the 1,3,5-trithian complexes precise energy barriers for the process have been obtained by detailed computer simulation of the static and dynamic spectra. Our results suggest that the magnitude of ΔG^≠ (298.15 K) for the 1,3-shift is largely dependent upon the skeletal flexibility of the ligand system. In this context we have investigated the X-ray crystal structure of the highly substituted trithian complex [W(CO)₅{β-$\text{SCH(Me)SCH(Me)SC}$H(Me)}].     

The early iron age of the Mössbauer era

The demonstration that the 14.4 keV level of⁵⁷Fe was an ideal Mössbauer example produced a veritable explosion in the discoveries of new physical phenomena. Among the important features of⁵⁷Fe are its ready availability and ease of preparation, its magnetic properties in many environments, the high intensity of its Mössbauer spectrum even at elevated temperatures, the relative sharpness of the Mössbauer lines, and the possibility of obtaining the resolution provided by this sharpness by relatively simple techniques. This paper hopes to capture some of the excitement and enthusiasm generated by the discoveries and demonstrations of the nuclear Zeeman effect, together with its polarization properties, the nuclear isomer shift, the quadrupole splitting, the temperature effect, temporal effects, nuclear hyperfine fields, transferred magnetism, the gravitational red shift, and many other new or newly elucidated phenomena.     

General boundary conditions for the wave equation around non-homogenous scatterers

To solve the wave equation inside a region that contains an inhomogenous dielectric material of arbitrary shape under the influence of an incoming wave, we establish a generalized boundary condition. The solutions inside a finite region resulting form a given incoming wave from the outside, are determined by a linear relation between the normal gradient and the function values on the boundary. This boundary condition is non-local and we show how it can be used in conjunction with the variational principle applied to an open system.     

Light-cone superspace and the ultraviolet finiteness of the N=4 model

Superspace in the light-cone frame takes a simple form. No auxiliary fields are necessary, and application to extended supersymmetries is straightforward. It is shown that the N=4 model, in a certain form of the light-cone gauge, is completely free of ultraviolet divergences in any order of perturbation theory. It follows that the β-function vanishes in any gauge, to all orders of perturbation theory. Our method differs from the conventional method in that we use only half the number of θ's as there are supersymmetry operators. All fields are unconstrained and independent of the $\text{θ}\text{'}\text{s}$.     

New formulation of quantum mechanics

A reformulation of the mathematical foundations of quantum mechanics is presented. This new framework is based on the concepts of measurement, generalized action, and a unique universal influence function. The main axiom is that the probability of a measurement outcome is the sum (or integral) of the influences between pairs of alternatives that result in the outcome when the measurement is executed. The framework provides answers to various puzzling questions of traditional quantum mechanics. Moreover, it gives a realistic model that extends the usual quantum mechanical formalism.     

Ion implantation doping and electrical properties of high-temperature ladder polymers

We report the first ion implantation doping studies on high-temperature ladder polymers and show that insulting films of the benzimidazobenzophenanthroline-type ladder polymer (BBL) can be doped by boron, argon, and krypton implantation to conductivities as high as 224 S/cm at a dose of 4.0 × 10¹⁶/cm² while retaining the excellent mechanical properties of the pristine films. Effects of dose (ions/cm²) and beam current density (microamps/cm²) on electrical conductivity at fixed ion energies are reported. The temperature dependence of the conductivity indicates that the implanted ladder polymer films are semiconductors. Spatially selective implantation, creating regions of conducting lines in an insulating matrix, which suggests microelectronic device applications of the ladder polymers, is demonstrated.     

On representation spaces in geometric quantization

The structure of the space of wave functions in the representation given by a complete strongly admissible polarization of the phase space is investigated. The conditions that the wave functions should be covariant constant along the real part of the polarization define the Bohr-Sommerfeld set of the representation containing the supports of all wave functions. There is a natural scalar product for the wave functions defined on the Bohr-Sommerfeld set. It is shown, for a real polarization, that the resulting Hilbert space of wave functions is not trivial if and only if the Bohr-Sommerfeld set is not empty.Partially supported by the National Research Council, Grant No. A8091.     

Distinguishing between N-methylated imidazolinones using mass spectrometry

Imidazolin-4-ones are a new class of herbicides which contain both an amide and amino nitrogen in a five-membered ring. During the manufacturing process, it is possible to methylate either nitrogen. This presented an interesting analytical problem in distinguishing between the two N-methylated derivatives of ASSERT® (a mixture of 6-(4-isopropyl-4-methyI-5-oxo-2-imidazolin-2-yl)- m- and p-toluic acid methyl esters) at low levels in a complex mixture. After developing a high-performance liquid chromatography method for separating and isolating components in the mixture, mass spectrometric techniques, which included electron impact (EI) and collisional activation decomposition (CAD), were used to distinguish between two isomeric N-methylated derivatives. The data from the El and CAD experiments enabled amidomethyl and aminomethyl structures to be assigned. Accurate mass measurements and proton nuclear magnetic resonance spectroscopy were used to support the assignments.