ABSTRACT
More than half of all instrumental methods of analysis involve the absorption or emission of light. Such instrumental methods can be referred to as
spectrochemical methods
. The science that deals with light and its absorption and emission by solutions and other material substances is called
spectroscopy
or
spectrometry
. The broad term for the instrument used is
spectrometer
, while a slightly more specific term (when a light sensor known as a phototube is used) is
spectrophotometer
. In spectrochemical analysis procedures, the degree to which light is absorbed, or the intensity of light that is emitted, is related to the amount of an analyte present in the sample tested. Thus the degree of light absorption and the intensity of light emission are the critical measurements. The electrical signal readout referred to in Figure 6.4 is, in the case of spectroscopy, an electrical signal that is related to the degree of light absorption or the intensity of light emission. The instrument readings mentioned in Figure 6.5 are the readings generated by the instrument as a result of this absorption or emission. See Figures 7.1 and 7.2.
