Instruments electronic developments

Electronic developments have revolutionized many types of laboratory equipment. Few instruments with dials are seen today, for instance. Digital readouts have taken over. While easier to use, estimating the amount of fluctuation of unstable signals is more difficult on a digital readout. There are also cases where an instrument s readout is more sensitive than its detection device, thereby causing unstable readings. For certain applications, a dial instrument may still be preferable. Electronic balances are now the rule rather than the exception. They are not only easy to use, but they generally require less service than mechanical ones. Prices have been considerably reduced in recent years. 

As we shall see, the solution conductivity depends on the ion concentration and the characteristic mobility of the ions present. Therefore, conductivity measurements of simple, one-solute solutions can be interpreted to indicate the concentration of ions (as in the determination of solubility or the degree of dissociation) or the mobility of ions (as in the investigations of the degree of solvation, complexation, or association of ions). In multiple-solute solutions, the contribution of a single ionic solute to the total solution conductivity cannot be determined by conductance measurements alone. This lack of specificity or selectivity of the conductance parameter combined with the degree of tedium usually associated with electrolytic conductivity measurements has, in the past, discouraged the development of conductometry as a widespread electroanalyti-cal technique. Today, there is a substantial reawakening of interest in the practical applications of conductometry. Recent electronic developments have resulted in automated precision conductometric instrumentation and applications... 

In the following section we will consider some of the applications of microprocessors in laboratory microcomputers, but we conclude this section with an illustration of the effects which electronic developments (and in particular microprocessors) have had upon analytical instruments by comparing an infrared spectrometer produced two decades ago with an equivalent model manufactured today. 

Mass spectrometry has become more useful In the support of electronic development and manufacturing processes. Fourier transform mass spectrometry, the latest advance in this analytical method, Is another step forward in versatility, sensitivity and reproducibility in analytical characterization, qualification and quantification of raw materials and contaminants as used in electronic devices. A review will be provided of basic instrument hardware and interfacing, significant operating parameters and limitations, and special inlet systems. Emphasis will be placed on material evaluation, process control and failure analysis. Data handling will be reviewed using appropriate examples encountered in material and failure analysis. 

The content of particulate PAHs can be measured with an instrument originally developed at ETH in Zurich (Burtscher et al., 1982). In this instrument, small soot particles that have accumulated a deposit of PAHs from combustion processes are selectively photo-ionized by UV light. After the electrons have been removed, positive ions are collected on an insulated paper filter, and the current from the charged paper filter is measured by means of a sensitive electrometer. The instrument can be calibrated against a PAH mixture, for example, one representative of vehicle exhaust, using the result from a gas chromatograph as reference. The instrument operates within the concentration range 1-2000 ngW. 

Rutherford s experiments opened the door to nuclear transmutations of all kinds. Atoms were bombarded by alpha particles, neutrons, protons, deuterons (iH), electrons, and so forth. Massive instruments were developed for accelerating these particles to very high speeds and energies to aid their penetration of the nucleus. The famous cyclotron was developed by E. O. Lawrence (1901-1958) at the University of California later instruments include the Van de Graaf electrostatic generator, the betatron, and the electron and proton synchrotrons. With these instruments many nuclear transmutations became possible. Equations for a few of these are as follows ... 

With regard to resolution, electron microscopy provides a powerful alternative which even allows the detection of single atoms. Eirst instruments were developed in the 1930s by Ruska (e.g. Knoll and Ruska 1932), who later received the Nobel Prize in physics for this achievement, and von Ardenne (1938). Two fundamental types are distinguished ... 

Developments such as that of the vacuum triode, cathode ray tube and, later, the transistor and the solid-state integrated-circuit device, had an enormous influence on the design and construction of instruments. Electronic systems can respond with lightning speed to an almost-zero signal. The glass ion-sensitive electrode was discovered in the early 1900 s, but its appearance in the pH meter had to wait for developments in electronics. 

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