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Chapter III CHN Analysis, FT IR …..
Many times it is given in the chart and tabular form to facilitate the user
to identify the specific bond vibrations from the frequency in wave numbers,
represented in the figure (3.3).
Figure: 3.3 A chart to identify specific bond vibrations in wave numbers.
There are mainly three types of instruments available, which are (1)
dispersive grating type, (2) multiplex type and (3) non-dispersive type. Variety
of infrared sources are developed depending upon requirements, which include
the Nernst glow-bar, incandescent wire sources, mercury arc, tungsten
filament lamp, etc. Good transducers such as, thermal, pyro-electric and
photo-conducting are also important in the detection and measurement of
infrared radiation. For different regions, different type of radiation sources,
optical systems and detectors are needed. The standard infrared
spectrometer is a filter-grating or prism-grating instrument covering range from
4000-650 cm -1 (2.5-15.4 μm). However, the grating instruments offer high
resolution that permits separation of closely spaced absorption bands,
accurate measurements of band position and intensities and high scanning
speeds for a given resolution and noise level. Modern spectrometers generally
have attachments that permit speed suppression, scale expansion, repetitive
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