Deactivation of biacetyl triplets by cyanocobaltate(III) complexes

The rate of electronic energy transfer from biacetyl triplets to Co(CN)_(5)(X)^(n–)(X = CN^–, MeCN, pyridine, N_(3)^–, H_(2)O, or SCN^–) is strongly dependent on the energy of the first spin-allowed d–d transition of Co(CN)_(5)(X)^(n–), and (for X = CN^–, N_(3)^–, and SCN^–) the direct and sensitized photosubstitution yields are the same, implying a common reactive state

Quantum Chemistry of Electrode Processes. II. Higher Activation Energies

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69659/2/JCPSA6-45-2-761-2.pd

Quantum Chemistry of Electrode Processes. I. General Relations for Electron Exchange between Electrode and Electroactive Species under Equilibrium and Nonequilibrium Conditions

It is assumed in this paper that at the electrode—solution interface there is molecular order of the electroactive species resembling solid‐state order. Specifically, it is assumed that next to the electrode is a layer of adsorbed neutral solvent molecules which are also ligands coordinated to the ions found in the interface. The mechanism of electron transfer from the electrode to the ion or the reverse from the ion to the electrode is assumed initially to involve a transition from either the electrode or the ion to the solvent molecule. This is followed by a transition of the electron from the solvent molecule to either the ion or the electrode. The two transitions involved in the net transfer of an electron across the interface are considered analogous to the charge‐transfer mechanism of spectroscopy. The wavefunctions representing the system at the interface are then of the same form as the charge‐transfer wavefunctions given by Mulliken.By considering the radiationless transition probabilities for the electron transitions in the interface system at the electrode, it is found that the usual current expressions result. By imposing the condition of zero net current at equilibrium the Nernst equation results. By further considering the polarization of the electrode under nonequilibrium conditions as a perturbation of the energy levels of the system, it is found that with the proper identification of terms the current expression for the polarized electrode results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71116/2/JCPSA6-43-9-3291-1.pd

Iodinated Aluminum(III) Corroles with Long-Lived Triplet Excited States

The first reported iodination of a corrole leads to selective functionalization of the four C–H bonds on one pole of the macrocycle. An aluminum(III) complex of the tetraiodinated corrole, which exhibits red fluorescence, possesses a long-lived triplet excited state

Hazard Assessment of Personal Protective Clothing for Hydrogen Peroxide Service

Selection of personal protective equipment (PPE) for hydrogen peroxide service is an important part of the hazard assessment process. But because drip testing of chemical protective clothing for hydrogen peroxide service has not been reported for about 40 years, it is of great interest to test new protective clothing materials with new, high-concentration hydrogen peroxide following similar procedures. The suitability of PPE for hydrogen peroxide service is in part determined by observations made when hydrogen peroxide is dripped onto swatches of protective clothing material. Protective clothing material was tested as received, in soiled condition, and in grossly soiled condition. Materials were soiled by pretreating the material with potassium permanganate (KMnO4) solution then drying to promote a reaction. Materials were grossly soiled with solid KMnO4 to greatly promote reaction. Observations of results including visual changes to the hydrogen peroxide and materials, times to ignition, and self-extinguishing characteristics of the materials are reported

Removal of Perfluorinated Grease Components from NTO Oxidizer

Perfluorinated greases are typically used as a thread lubricant in the assembly of non-welded nitrogen tetroxide (NTO) oxidizer systems. These greases, typically a perfluoroalkylether, with suspended polytetrafluoroethylene (PTFE) micro-powder, have attractive lubricating properties toward threaded components and are relatively chemically inert toward NTO oxidizers. A major drawback, however, is that perfluoroalkylether greases are soluble or dispersible in NTO oxidizers and can contaminate the propellant. The result is propellant that fails the non-volatile residue (NVR) specification analyses and that may have negative effects on test hardware performance and lifetime. Consequently, removal of the grease contaminants from NTO may be highly desirable. Methods for the removal of perfluorinated grease components from NTO oxidizers including distillation, adsorption, filtration, and adjustment of temperature are investigated and reported in this work. Solubility or dispersibility data for the perfluoroalkylether oil (Krytox(tm)143 AC) component of a perfluorinated grease (Krytox 240 AC) and for Krytox 240 AC in NTO were determined and are reported

A simple computer circuit for automatic spectrophotometric analysis of binary mixtures by differential reaction rates

A simple analogue computer circuit, for application with a continuous reading spectrophotometer to give automatic analysis of binary mixtures of closely related substances using a differential reaction rate technique, is described. The circuit solves the simultaneous equations of the Method of Proportional Equations for the concentrations of the components in the mixture. The method is useful for first- or pseudo-first order competitive reactions. A timing circuit automatically supplies the absorbance (converted as described from the transmittance) of the reacting solution at two chosen times during the reaction, to the computer. The output voltages are adjusted within the circuit to read directly in units of concentration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32026/1/0000069.pd

The anodic strippin voltammetry of trace silver solutions employing graphite electrodes application to silver analysis of rain and snow samples from silver iodide seeded clouds

The characteristics of the anodic stripping curves obtained from 10-11-10-7 M Ag+ have been studied using pyrolytic graphite and wax impregnated spectrographic grade carbon electrodes. It was found that the stripping curves on pyrolytic graphite electrodes (PGE) had essentially only one sharp dissolution peak, while those for wax impregnated carbon (SGE) exhibited multiple dissolution peaks. The nature of the Ag deposits was studied by X-ray fluorescence employing an electron microprobe which showed that PGE had a few preferred sites for deposition but the SGE exhibited a uniform distribution of the deposit. The optimum solution conditions, electrode pretreatments, and procedure are described, as well as the results of the analyses of snow samples containing 10-8-4 x 10-11 M Ag+.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32817/1/0000191.pd

A polarographic method for following the rates of cholinesterase-catalyzed hydrolyses of acetylthiocholine

A rapid and simple polarographic method for following the rates of the cholinesterase-catalyzed hydrolysis of acetylthiocholine and the rates of inhibition of this hydrolysis is described. This method has the advantage that it can follow quite rapid reactions, as meaningful data can be obtained after 10 sec of mixing of the solutions. The method follows the rate of increase of the anodic polarographic wave of thiocholine produced by the hydrolysis. The validity of the method was determined by comparing the rates of production of thiocholine spectrophotometrically and polarographically. Also the values of Km for the hydrolysis, and Km and K1 for the inhibition reaction of neostigmine were determined and compared to values reported in the literature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31994/1/0000036.pd

Preconcentration techniques for trace analysis via neutron activation

A review is given of the methods that have been proposed for enrichment of trace elements in samples that are to be analysed by neutron-activation methods. The emphasis is on classification of methods, with full illustrations by means of practical examples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34169/1/0000457.pd