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|Title:||Microcomputer-Controlled Instrumentation for Analytical Conductance Measurements Using the Bipolar-Pulse Technique|
|Author(s):||Geiger, Richard Francis, Jr.|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The measurement of solution conductance can provide useful information for a wide variety of chemical systems. One method of making rapid and accurate conductance methods is by using the bipolar pulse technique. In this method, two square-wave voltage (or current) pulses, which have opposite polarity but equal duration and magnitude, are applied to the conductance cell. The resulting current (or voltage) may be instantaneously sampled at the end of the second pulse, or may be rectified and integrated. The theoretical errors inherent in this technique are described, and constraints on the use of bipolar pulse techniques are developed.
Two microcomputer-controlled instruments employing the bipolar pulse technique are described and evaluated. The first instrument is capable of making measurements only with sampled voltage pulses. Its measurement range extends from 5 x 10('1) ohms to 5 x 10('7) ohms with 1% accuracy. The second instrument is capable of all four modes of measurement: voltage or current pulses and sampled or integrated measurement. Its measurement range extends from 1 x 10('-1) ohm to 5 x 10('7) ohms with 1% accuracy. Measurement precision, drift, and speed were also characterized for each instrument. An optimization scheme was developed to indicate the proper pulse duration and measurement mode to use for a given resistance.
The operating software in a computer-controlled instrument is often at least as important as the hardware. Programs have been developed to communicate to the operator, optimize the instrumental parameters for the best possible measurement, and average a specified number of measurements. Communication between the controlling microcomputer and a larger laboratory microcomputer is also possible, for long-term storage of data or for program development.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2014-12-15|