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SPECTROMETRY 1. General 2. High Energy 3. Medium Energy 4. Low Energy 5. Mass Spectrometry 6. References |
SPECTROMETRY This paper was presented for translators at the 36th Annual Conference of the American Translators Association, 1996. Copyright: American Translators Association. All rights reserved. This document may not be reproduced without the written permission of the American Translators Association. Presented here by permission, and slightly modified for this web page. CHEMICAL ANALYSIS: SPECTROMETRY Abstract: Analysts use various kinds of interaction between matter and energy to identify elements to identify elements and compounds, and to determine their quantities. This paper is an introduction to the terminology used.1. General Spectrometry: measurement of interaction between matter and electromagnetic radiation. (Mass spectrometry does not fit this definition.) Electromagnetic radiation includes the spectrum from ultra-high-frequency radio waves to gamma rays. That covers about six orders of frequency or wavelength. Very rarely if at all would any one person (or even one laboratory) work across the entire range. Table 1
With this wide range of frequencies/wavelengths, the equipment needed is very different in the different ranges. While we tend to think of optical equipment, that is useful only in the middle of the range, although that will get most of the attention here. Closely related terms:
Spectrometry includes:
Atoms and molecules have only certain distinct (discrete) amounts of energy (energy levels). Relatively small amount of energy are involved in rotation of molecules, and those measurements are done with far infrared and microwave spectrometry. More energy in involved in vibrations between atoms or groups of atoms (infrared). Still more energy is involved in changes of the electronic structure (visible, ultraviolet, X-ray) and nuclear structure (gamma ray). Spectrometry is primarily measurement of energy absorbed or emitted as atoms or molecules change from one distinct energy level to another. Each such change involves a fixed amount of energy, which is in a package called a quantum or photon. While these photos can be considered as elemental particles, it is often convenient (or at least usual) to think of them as having wave motion with specific frequencies and wavelengths which are linked to their energies:
Most of these definitions give inconveniently large or small numbers, so more convenient ones are used in different spectral ranges (see Table 1). Three of them may give trouble:
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