Anthony F. Fucaloro

Enhanced line emission from laser-produced plasmas

This communication reports the first systematic study on background gas‐induced, spectral line emission enhancement from laser‐produced plasmas. Line emission from aluminum plasmas was enhanced by factors of up to 35 by the introduction of He, Ne, Xe, or N2. The enhancement has been attributed to three‐body recombination.

Linkage isomerization of [Co(NH3)5ONO]2+ in poly(vinyl alcohol)

Abstract The rate of linkage isomerization of nitritopentaamminecobalt (III) to the nitro form was measured spectrophotometrically in poly(vinyl alcohol) sheets at three temperatures. The nitrito complex was generated photochemically.

FLUORESCENCE QUENCHING OF INDOLE BY DIMETHYLFORMAMIDE

Abstract— The effect of dimethylformamide on the lifetime (T) and quantum yield (F) of indole has been determined. Negative Stern‐Volmer deviations prevail for T and F, but F0/F T0/T at all DMF concentrations. The deviation between F0/F and T0/T is ascribed to changes in F0 and T0 induced by the change in solvent composition at the higher quencher concentrations.

Spectroscopic evidence for a delocalized excited state in the magnus salts

Abstract The polarized single-crystal spectra of the Magnus salts [Pt(NH 3 ) 4 ][PtCl 4 ], [Pd(NH 3 ) 4 ] [PtCl 4 ], [Pt(NH 3 ) 4 ] [PdCl 4 ], and [Pd(NH 3 ) 4 ][PdCl 4 ] have been obtained in the quartz ultraviolet and visible regions. These results provide strong evidence for a delocalized excited state being associated with the intense ultraviolet transition found in the spectra of the Magnus salts. One thus has available an important new criterion for the evaluation of the theoretical treatments of these systems.

CONFORMATIONAL FLUCTUATIONS IN ∝aL-CHYMOTRYPSINOGEN A POWDERS

Abstract— The average fluorescence lifetime for the tryptophan excited state decay in a‐chymotrypsinogen A is independent of hydration up to 0.15 g H2O/g protein. A sharp decrease in lifetime occurs between 0.15 and 0.18 g H2O/g protein, followed by a gradual decrease toward the solution value. This behavior, in a protein where the exposure of the tryptophans to solvent is minimal, is in marked contrast to that observed in bovine serum albumin where at least one of the two tryptophans can interact directly with water.

A technique for determining relative transition moments from stretched film spectra

Abstract A method is presented for removing ambiguities inherent in determining relative transition moment directions by the stretched film technique.

The effect of environmental rigidity on nonradiative decay in chromium(III) amines

Abstract The lifetimes of Cr(NH 3 ) 6 3+ and the Cr(cyclam)(NH 3 ) 2 + complexes, both protiated and deuterated, have been recorded in aqueous polyalcoholic and DMSO solutions in the temperature range that includes the change from a rigid glass to a fluid. A small but distinct lifetime reduction is associated with increased solvent mobility in the protiated species but not in the deuterated complex. This is interpreted to indicate that increasing anharmonicity in accepting modes enhances the nonradiative rates.

Determination of molar refractions and Abraham descriptors for tris(acetylacetonato)chromium(III), tris(acetylacetonato)iron(III) and tris(acetylacetonato)cobalt(III)

We have determined molar refractions of tris(acetylacetonato)chromium(III), tris(acetylacetonato)iron(III) and tris(acetylacetonato)cobalt(III). Although the d-electron structures of the three metal centres differ significantly, the three molar refractions are actually quite close to each other. We then used these molar refractions to determine the Abraham E-descriptor, we calculated the V-descriptor by McGowans method, and then used literature data on solubilities and water–solvent partitions to obtain the rest of the set of descriptors for the three tris(acetylacetonato) complexes. If we take E as the average of those for the chromium, iron and cobalt complexes, we can use limited literature data to obtain the full set of Abraham descriptors for the tris(acetylacetonates) of vanadium(III), yttrium(III), samarium(III), lanthanum(III) and neodymium(III). For the eight complexes, the descriptors vary regularly with complex molecular weight. These show that the complexes are quite polarizable, have zero hydrogen-bond acidity and significant hydrogen bond basicity. From the sets of Abraham descriptors, a very large number of physicochemical properties can be predicted for the eight acetonylacetonates.

A Volumetric Study of Aqueous Primary Alcohols as Functions of Concentration and Temperature

AbstractDensity measurements of aqueous solutions of ethanol, 1-butanol, and 1-pentanol made in this laboratory along with those made for methanol, ethanol, and 1-propanol by Benson and Kiyohara form the basis for a volumetric analysis of solutes possessing both hydrophilic and hydrophobic regions as functions of both concentration and temperature. The extent of deviation of the modified volume function with mole ratio was shown to provide a quantitative measure of non-ideality. The deviations from ideality for dilute solutions are mediated by the solvated regions surrounding the hydrophobic region and are a function of the number of methylene groups. This region was shown to consist of water exhibiting a higher degree of hydrogen bonding than that of bulk water in accordance with previous studies. Moreover, the partial molar volume at infinite dilution for these primary alcohols is nearly a linear function of the number of methylene groups.