Pentafluorophenylchlorine(III) difluoride

Pentafluorophenylchlorine(III) difluoride has been prepared by the oxidation of pentafluorophenyl chloride at 117°C with elemental fluorine.     

Tail Properties of Correlation Measures

We study the tail properties of a class of Borel probability measures, called correlation measures. We show that (i) there exist correlation measures with exponentially decaying tail probabilities, and (ii) roughly speaking, no correlation measure may have smaller tail probabilities than a Gaussian measure.     

Optimal block diagonal scaling of block 2-cyclic matrices

We describe a class of optimal block diagonal scalings (preconditionings) of a symmetric positive definite block 2-cyclic matrix, generalizing a result of Forsythe and Strauss [1] for (point) 2-cyclic matrices.     

Displacement reactions of 5-chloro-4-phenylazopyrazoles

3-Methyl or 3-phenyl-5-chloro-1-phenyl-4-phenylazopyrazole with primary amines, sodium polysulfide and sodium azide yielded amines, disulfides and 2,4-dihydropyrazolo[3,4-d]-1,2,3-triazoles respectively. 4-Amino-5-anilino-1,3-diphenylpyrazole was also prepared and characterized.     

Influence of deformation on the mobility and lifetimes of charge-carriers in anthracene crystals

Direct determination of the mobilities and lifetimes of electrons and holes in undeformed and in dislocated single-crystals of ultra pure anthracene reveals fresh insights into the mechanism of carrier trapping. The deformation introduced electron traps at depths of approximately 1.0 eV but was found not to affect hole transport. Such traps are considered to be due to impurities preferentially introduced into the lattice as a result of the generation of the additional dislocations.     

On the regularizing properties of the GMRES method

Summary. The GMRES method is a popular iterative method for the solution of large linear systems of equations with a nonsymmetric nonsingular matrix. However, little is known about the behavior of this method when it is applied to the solution of nonsymmetric linear ill-posed problems with a right-hand side that is contaminated by errors. We show that when the associated error-free right-hand side lies in a finite-dimensional Krylov subspace, the GMRES method is a regularization method. The iterations are terminated by a stopping rule based on the discrepancy principle. Received November 10, 2000 / Revised version received April 11, 2001 / Published online October 17, 2001