Effects in polarography attributable to specific adsorption of depolarizers

Summary Some effects in polarography produced by specific adsorption of the oxidised form of the depolarizer are discussed. It is suggested that this adsorption may lead to maxima in d.c. polarography when the depolarizer concentration is small and the solution has a high electrical conductivity. In normal pulse polarography specific adsorption of the oxidised form of the depolarizer may produce a maximum on the polarographic wave which is not basically due to streaming of the solution. Specific adsorption also leads to an increase in sensitivity in a.c. polarography and in R.F. polarography it produces asymmetry in the wave. Experimental results for lead ion in HClO₄ solutions containing varying amounts of Br^– ion suggest that as the concentration of Br^– increases, although the adsorbed species is probably at first PbBr⁺, eventually undissooiated PbBr₂ is strongly adsorbed.

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Zusammenfassung Die Wirkung der spezifischen Adsorption der oxydierten Form des Depolarisators auf polarographische Bestimmungen wird erörtert. Diese Adsorption kann bei der Gleichstrompolarographie Maxima verursachen, wenn die Depolarisationskonzentration niedrig ist und die Lösung eine hohe elektrische Leitfähigkeit besitzt. Bei der normalen Pulspolarographie kann die spezifische Adsorption der oxydierten Form des Depolarisators auch ein Maximum verursachen, daß grundsätzlich nicht von einer Strömung der Lösung herrührt. Bei der Wechselstrompolarographie führt die spezifische Adsorption auch zu einer Zunahme der Empfindlichkeit und bei der Radiofrequenzpolarographie wird eine Asymmetrie der Stufen hervorgerufen. Versuche mit Bleiionen in perchlorsauren Lösungen mit verschiedenen Gehalten an Bromid zeigten, daß bei steigenden Br^–-Konzentrationen anfangs wahrscheinlich PbBr⁺, schließlich jedoch undissoziiertes PbBr₂ stark adsorbiert wird.

     

HE(I) Photoelectron spectra of 1,2-ethanediol in the liquid and gas phases

Nine bands in the He(I) gas-phase photoelectron spectrum of 1,2-ethanediol are assigned by means of ab initio calculation and by comparison with the sp     

Field-dependence of carrier screening in non-linear transport theory

Modifications to the high-field Boltzmann transport equation are obtained to include ab initio self-consistent non-equilibrium free-carrier screening of the scattering rates. For quasi-static homogeneous fields the screening involves a Lindhard-like dielectric function which is field-dependent via the carrier distribution function and the carrier energetics.     

The post-post-Newtonian problem in classical electromagnetic theory

We find the Lagrangian to order c^?4 for two charged bodies (with $\text{e}{}_1\text{m}{}_1\text{=}\text{e}{}_2\text{m}{}_2$) in electromagnetic theory. This Lagrangian contains acceleration terms in its final form and we show why it is incorrect to eliminate these terms by using the equationsof motion in the Lagrangian as was done by Golubenkov and Smorodinskii, and by Landau and Lifshitz. We find the center of inertia and show that the potential energy term does not split equally between particles 1 and 2 as it does in the Darwin Lagrangian (Lagrangian to order c^?2). In addition to the infinite self-energy terms in the electromagnetic energy-momentum tensor, which are eliminated using Gupta's method, some new type of divergent terms are found in the moment of electromagnetic field energy and in the electromagnetic field momentum which cancel in the final conservation law for the center of inertia.     

Square wave polarography and some related techniques

The theory of square wave polarography is reviewed, and methods for obtaining increased sensitivity in A.C. polarography are outlined, including a new technique which makes use of an amplitude-modulated radio-frequency polarizing current. This R.F. technique can also be used to study the kinetics of very rapid electrode processes.     

Time-dependent-thermal-lensing (TDTL) studies on gas-phase azulene

Several aspects of the time-dependent-thermal-lensing (TDTL) technique were explored experimentally, including pressure effects, risetime behavior and falltime behavior. The experiments were performed using azulene vapor excited to high vibrational energies (≈ 17000 cm^?1). It was found that the energy appears in translational degrees of freedom at very early times, but the intrinsic limitations of the technique permitted only an estimate of the V-T rate constant for excited azulene deactivation by krypton. The result is discussed in terms of other recent experiments, and it is tentatively concluded that deactivation of excited azulene by unexcited azulene molecules may proceed primarily by a V-V process.     

Zizaane sesquiterpenes. Synthesis of the coates-sowerby tricyclic ketone

The cycloadduct (5) , which is conveniently prepared by irradiation of (4), is converted $\text{via}$ a 4-step sequence, into the tricyclic ketone (2$\text{a}$) and its epimer (2$\text{b}$); the sequence formally completes a new total synthesis of (±)-zizaene (1) and its Me-epimer.