Über 2,4-Difluorzimtsäure

Zusammenfassung Aus 2,4-Difluortoluol wurden nach üblichen Methoden 2,4-Difluorbenzaldehyd und 2,4-Difluorzimtsäure hergestellt.     

Countably many simultaneous random changes of time scales

Simultaneous changes of time scales of the components of a vector Markov process are defined and developed. Measurability properties, Dynkin's lemma, and the strong Markov property are established for the transformed process.     

Hydrogen in perovskites: Mechanism of solubility, chemical state, effect on electron subsystem, phase transformation

The phenomena of hydrogen/water solubility in YBa₂Cu₃O_7-δ and BaCeO₃ undoped and doped by Y and Nd are considered. New experimental data as well as recently published data have been accumulated to discuss the chemical state of protons, taking into account the fairly strong interaction of the protons with the electron subsystem. Phase transformation of the studied oxides induced by hydrogen/water intercalation were revealed by the investigations of thermal effects, X-ray diffraction, Raman spectroscopy, inelastic neutron scattering and nuclear quadrupole resonance. Paper presented at the 5th Euroconference at Solid Statre Ionics, Benalmádena, Spain, Sept. 13–20, 1998.     

Intramolekulare diels-alder-reaktionen mit substituierten 1,2,4,5-tetrazinen und 1,2,4-triazinen

1,2,4,5-tetrazines as well as 1,2,4-triazines carrying sidechain dienophiles react in an intramolecular Diels-Alder cycloaddition with inverse electron demand to yield novel bicyclic pyridazines and pyridines.     

The mössbauer effect: A potentially ideal probe into Brownian motion

We calculate the Mössbauer spectrum of nuclei embedded in spheres of radius on the order of 1 μm which are suspended in a liquid. We demonstrate that the Mössbauer effect is an ideal means for testing the deductions based upon a generalized Langevin equation which takes into account the effects of acceleration memory on the force and torque of the liquid on a sphere and for studying, generally, the detailed statistical dynamical behavior of Brownian particles. The spectrum is expressed in terms of an integral over an integrand consisting of standard functions. Experimental desiderata are discussed and a list of sample experimental parameters given.     

Surface segregation in alloys: Existence of surface miscibility gaps within regular solution theory

Much attention has been paid to the relationship between the bulk phase diagram and the phenomena of surface segregation. There is no reason to believe, however, that the equilibrium phase boundaries for the surface region are identical to those of the bulk. In this paper, we have derived the surface phase boundaries within the regular solution approximation using pairwise interactions. We find that the concept of phase separation for the surface region is not important if the surface phase is in equilibrium with the bulk and the bulk is in a region of solid solubility. The experimental conditions employed in some studies, however, lead to nonequilibrium states (due to quenching). For these cases, surface phase separation may be expected under typical experimental conditions.     

New studies of the Si-SiO2 interface using auger sputter profiling

We have made new measurements of the morphology and chemistry of “state of the art” thermally grown Si-SiO₂ interfaces using Auger sputter profiling. With improved experimental technique and theoretical treatment of electron escape depth and ion knock-on effects, we find the width of the interface to be about 2.0 nm. This width is probably due to an undulating interface, the period of which is less than 100 μm. Any SiO_x present resides in a connective layer no greater than 0.8 nm thick at any point.