Good spectroscopic practice

Good spectroscopic practice is a set of pragmatic practical actions and operations 

The following is a list of some of the more important steps that have to be ensured. 

The spectrometer is in a proper state of calibration and is well maintained at all times. 

The solution concentration is as free as possible from weighing, volumetric and temperature errors. 

The compound to be examined is completely dissolved ultrasonic treatment as routine is highly recommended. 

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All these processes, together with instrumental effects, combine to distort or degrade the quality of the spectrum. The competent spectroscopist recognises these dangers and seeks to minimise their impact. More will be said about good spectroscopic practice in Section 3.1. 

Figure 10. Quality information and knowledge based on good spectroscopic practice.

Reliability of the data quality should be linked to performance standards for the spectrometer, in addition to having a regular maintenance programme. Quality must be built into analytical procedures, based on the firm foundation of good measurement data and sample practices enshrined in good spectroscopic practice. This process is illustrated in Fig. 10. 

A chroaatogreuB provides information regarding the complexity (numlser of components), quantity (peak height or area) and identity (retention par uleter) of the components in a mixture. Of these parameters the certainty of identification based solely on retention is considered very suspect, even for simple mixtures. When the identity can be firmly established the quantitative information from the chromatogram is very good. The reverse situation applies to spectroscopic techniques which provide a rich source of qualitative information from which substance Identity may be inferred with a reasonable degree of certainty. Spectroscopic Instruments have, however, two practical limitations it is often difficult to extract quantitative... 

The quantities determined directly by the spectroscopic analysis as performed for hot stars are effective temperature Tef f surface gravity g and element abundances. Of course, this is not sufficient to place a star in the HR diagram. This is possible only with further knowledge of either luminosity, radius, mass or distance of the star. However, uncertainties in these quantities (which are usually much larger than the uncertainties in Te and g) directly translate into the HR diagram. On the other hand, theoretical evolutionary tracks can be easily expressed in terms of Teff and g without loss of precision. It is therefore good practice to discuss the results of spectroscopic analyses directly in a (log Te -log g) diagram as we shall do in this paper. 

The situation, however, is different for the infrared spectroscopic measurements with opposed anvil cells. The source beam in commercial Fourier transform infrared spectrometers is generally focused to about 1 cm diameter at the sample, whereas the diameter of the gasket hole in the high pressure cell is only about 0.3 mm. Therefore, a source beam condensing system is required in order to obtain infrared spectra with a good signal-to noise ratio. Commercial beam condensers (4X, 6X) could, in principle, be adapted for these purposes. In practice, however, the mirrors of the... 

The host materials that are utilized in laser systems must exhibit adequate transparency, mechanical strength, and thermal properties. In addition, the material must be able to sustain a precise optical polish, and be cast or grown adequately within reasonable economic and time constraints. The host must afford the impurity ions the type of spectroscopic properties that are appropriate for good laser performance. As a result of the numerous requirements, not many materials turn out to be useful in practical circumstances. Below, the nature of glasses and crystals is discussed, and the important physical properties are briefly outlined. 

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