It is shown that the commonly held view of a sharp Fe K edge must be modified if the decay pathways of the series of resonances converging to the K thresholds are adequately taken into account. These resonances display damped Lorentzian profiles of nearly constant widths that are smeared to impose continuity across the threshold. By modeling the effects of K damping on opacities, it is found th...

A technique to investigate photodissociation kinetics on a nanosecond time scale has been devised for molecular ions generated by multiphoton ionization (MPI) using mass-analyzed ion kinetic energy spectrometry. The branching ratio or rate constant has been determined for the photodissociation of the n-butylbenzene, bromobenzene, iodobenzene, and aniline molecular ions generated by MPI at 266 n...

A modified cytochrome c peroxidase was prepared by reconstituting apocytochrome c peroxidase with protoheme in which both heme propionic acid groups were converted to the methyl ester derivatives. The modified enzyme reacted with hydrogen peroxide with a rate constant of (1.3 +/- 0.2) x 10(7) M-1 s-1, which is 28% that of the native enzyme. The reaction between the modified enzyme and hydrogen ...

The ionization constant (pKa) and limiting ionic mobility of 3-chlorotyrosine (CT) and 3-nitrotyrosine (NT) were determined in capillary zone electrophoresis (CZE) in a wide pH range. Measurements were carried out in a poly(ionic liquid) (PIL) modified capillary at a low pH (1.80-4.00) and a bare fused capillary at an upper pH (3.00-11.00). Electrostatic interaction between analytes and inner w...

Product ion yields in post-source decay and time-resolved photodissociation at 193 and 266 nm were measured for some peptide ions with a histidine residue ([HF(6) + H](+), [F(6)H + H](+), and [F(3)HF(3) + H](+)) formed by matrix-assisted laser desorption ionization (MALDI). Compared with similar data for peptide ions without any basic residue reported previously, significant reduction in dissoc...

The Coupled Chemical and Physical Dynamics (CPCD) model of matrix assisted laser desorption ionization has been restricted to relative rather than absolute yield comparisons because the rate constant for one step in the model was not accurately known. Recent measurements are used to constrain this constant, leading to good agreement with experimental yield versus fluence data for 2,5-dihydroxyb...

It has been assumed for a long time that the ionization of atoms by ions must in one form or another play an important r6le in the phenomena of gas discharges. This assumption found its mathematical expression in the well-known theory of Townsend. Only recently, however, have the elementary effects of the ionization by ions been experimentally investigated. The ionization of noble gas atoms by ...

The results of the measurements of ionization due to the beta and gamma-radiations near the ground surface from 1967 through 1969 are reported, and are discussed comparing with those obtained from 1963 through 1966. The ionization due to the beta-radiation decreased gradu ally, and the mean value for this period is about I J at one meter above the ground surface, and that by the gamma-radiation...