A METHOD OF RECORDING a-c. POLAROGRAMS ON A CONVENTIONAL d-c. POLAROGRAPH

Abstract

An increase in the usefulness of the recording polarograph is obtained by a modification which allows either a-c. or d-c. polarogra~ns to be obtained from it.A description of such a modification performed on the Sargent Model XXI is given in detail. A comparison of a-c. and d-c. polarography is made and illustrated by polarograms obtained from this instrument. INTRODUCTIONPolarography with alternating currents has been investigated by a nunlber of authors but the most estensive work is that of Breyer et al. (vide ilzjra). Basically the method consists of impressing a sinall sinusoidal alternating voltage of low frequency on the direct potential applied to a dropping mercury electrode. This results in an applied e.m.f. which varies between limits determined by the amplitude of the a-c. voltage (AE, Fig. 1). Should the current be higher a t the upper limit than a t the lower limit of this voltage variation (as on the rising portion of the d-C. polarogram) an alternating current AI would be produced. This alternating current is measured as a function of the impressed direct voltage resulting in a plot which is esseiltially the derivative 'iCia?~uscript

Light Isotopes, Extinct Radioisotopes, and Gamma-Ray Lines from Low-Energy Cosmic-Ray Interactions

“…In considering the origin of the low energy cosmic rays in Orion, we distinguish the problem of the acceleration from that of the injection of the particles into the accelerator. The proposed acceleration mechanisms are shock acceleration, due to shocks associated with the winds of O and B stars (Nath & Biermann 1994) or shocks produced by colliding stellar winds and supernova explosions (Bykov and Bloemen 1994), and stochastic acceleration, due to gyroresonance with cascading Alfvén turbulence in the accretion disk of a black hole (Miller & Dermer 1995). The proposed injection sources are the winds of Wolf Rayet stars (the WC composition, Ramaty et al 1995a), the ejecta of supernovae from massive star progenitors (c.f.…”

Simplified Conversion of a Direct-Current Polarograph to a Low Frequency, Alternating-Current Instrument.

“…primarily toward the use of polarographic techniques in the study of pesticides and their residues. Considerable data have been accumulated on the use of this technique in the pesticide field (1,(4)(5)(6). In our laboratory, great value and versatility was found in the interchangeable use of the d.c. and a.c. methods, an outstanding instance being the development of an analytical procedure involving the use of a polarograph for the determination of total bromide on crop materials («)• LITERATURE CITED Under favorable conditions, most commercial mass spectrometers can just detect 10-50 v.pm.…”

Stochastic Particle Acceleration near Accreting Black Holes

“…Observations of out owing radio-emitting components following transient X-ray events in galactic X-ray novae and gamma-ray ares in blazars are in accord with this scenario.{ 3 { systematically investigate the plasma processes responsible for stochastic particle acceleration along with the energy-loss processes which impede particle energization. Application of this work to ion abundance enhancements in galactic black holes is considered separately (Miller & Dermer 1995). In x 2.1, we describe the geometry of our model for stochastic particle acceleration in a black hole magnetosphere, and establish standard parameters for the magnetic eld strength using equipartition arguments.…”