Current Sampling Time Research Articles

A “Universal Time” system for ASDEX upgrade

For the new generation of intelligent controllers for plasma diagnostics, discharge control and long-pulse experiment control a new time system supporting steady state real-time operation has been devised. A central unit counts time at nanosecond resolution, covering more than the experiment lifetime. The broadcast time information serves local units to perform application functions such as current time readout, trigger generation and sample time measurement. Time is treated as a precisely measured quantity like other physical quantities. Tagging all detected events and sampled values with measured times as [value; time]-entities facilitates real-time data analysis, steady state protocolling and time-sorted archiving.

Optimization of parameters for differential pulse voltammetry at the hanging mercury drop electrode

AbstractThe detection limit of differential pulse voltammetry at a hanging mercury drop electrode is investigated. The most important result of this study is that very small pulse amplitudes considerably improve the signal‐to‐background ratio and lead to lower detection limits. Due to the fact that (in practice) the background current does not originate only from capacitive properties of the electrode, an optimal pulse duration also exists, which guarantees the highest signal‐to‐background ratio. It is shown that the background current consists of the capacitive current and a very noisy but, on average, constant component, presumably of a faradaic nature that originates from impurities. The effects of the prepulse time, the pulse amplitude, the pulse duration, the step height of the staircase ramp, and the duration of the current sampling time on the signal and background intensity and noise are described.

Kinetic currents in normal pulse polarography (NPP): Current-potential curves for an electrode process with a preceding chemical reaction (ce mechanism)

A theoretical equation for the current-potential curves in NPP of a CE mechanism with non-Nernstian behavior is derived. Thus, the corresponding expression for a reversible charge transfer reaction has been obtained as a limiting case of the general solution. These equations allow us to examine the dependence of the polarograms and E 1 2 − values on both the rate constants and the equilibrium constant of the chemical reaction, as well as the effect exerted on the current-potential curves by the electrode reaction parameters (α and k s). The range of the rate-constant values of the chemical reaction that may be determined by using Normal Pulse Polarography as a function of the current sampling time is also discussed.

The optimization of the current sampling time in pulse polarography

A method for computing the approximate value of the non-faradayic component of the total decay current in a pulse polarographic experiment is described. Undesirable effects of such component are discussed. The method employed is simpler than computing the non-faradayic current from RC measurements and has the advantage of being applied under actual polarographic working conditions.

Application of staircase voltammetry with a varied current sampling time

Application of staircase voltammetry with a varied current sampling time

Staircase voltammetry with varied current sampling times: Theory for diffusion controlled, rate controlled, and mixed rate and diffusion controlled electrode reactions

Summary The theory for staircase voltammetry with a varied current sampling time has been derived for the cases of reversible, irreversible, and quasireversible electrode reactions. The equations derived have been used to calculate theoretical voltammograms employing several different values of the electrode reaction parameters k s and α n a and several values of the experimentally controllable step time, step size and current sampling time. The current sampling time is shown to be an important parameter in the application of staircase voltammetry to analytical and kinetic studies.

Application of staircase voltammetry with a varied current sampling time

Summary The technique of staircase voltammetry with a varied current sampling time has been evaluated with regard to its application in electrochemical kinetic studies. Instrumentation for staircase voltammetry and procedures to implement the technique and evaluate the data obtained are described. Experiments involving reactions with known kinetic parameters were used to evaluate the technique itself and the recently derived theory for staircase voltammetry.