2012 Product Catalogue

Specac Product Catalogue 2012 | A-Z of IR
A-Z of IR
Diffraction
The bending of light around the edge of an
opaque body, or through a narrow slit, resulting
in a series of alternately high and low intensities
in the shadow of the obstacle.
Diffuse reflection
The random reflection resulting when a beam of
light reflects off a rough, matt surface e.g.
powder or fibre.
Dispersive Instruments
Infrared spectrometers that use a grating or
prism to disperse Infrared radiation into its
component wavelengths before detecting them.
This type of instrument is less widespread since
the arrival of FTIR spectrometers.
DRIFTS (Diffuse Reflectance Infrared Fourier
Transform Spectroscopy)
A reflection sampling technique making use of
the phenomenon of diffuse reflectance.
E
Evanescent wave
A standing wave of radiation set up in an ATR
crystal at the interface with the sample. The
wave penetrates into the sample and an Infrared
spectrum can be obtained.
F
Far IR
Infrared radiation between 400 and 10 cm -1 .
Fluorolube
Polymer of trifluorovinyl chloride (-CF2-CFCl-)x
used for the preparation of mulls. Unlike Nujol, it
doesn’t mask CH stretch bands.
Fourier Transform
The integration performed upon an interferogram
to produce an Infrared spectrum.
Fourier Transform Infrared (FTIR)
Spectrometer
The instrument used for FTIR spectroscopy.
FTIR Spectroscopy
A method of obtaining an Infrared spectrum by
measuring the interferogram of a sample using
an interferometer, then performing a Fourier
Transform upon the interferogram to obtain
the spectrum.
G
Germanium
Element, atomic number 32, atomic weight
72.6:a gray-white metallic semiconductor. Its high
refractive index (4.01) makes it an important
material for ATR crystals, used to analyze highly
absorbing samples.
Golden Gate
Specac’s world-famous single reflection ATR
accessory, analyzing almost all sample types:
hard solids, to powders, to corrosive liquids, to
fibres. The Golden Gate is the world’s most
versatile sampling system. The standard
Diamond Golden Gate uses a type IIa diamond
as the ATR element for unparalleled optical
sensitivity, while diamond’s unique physical
strength makes it ideal for excellent contact with
the hardest of solids. Its tremendous chemical
stability allows it to withstand corrosive liquids.
Other Golden Gate versions available, to
accommodate various types of sample, include a
Germanium Golden Gate , whose high refractive
index is useful for highly absorbing samples, and
a heatable version for high temperature analysis.
Grazing angle reflection
An optical phenomenon occurring when the
incident Infrared radiation strikes a sample,
deposited on a reflective material, at an angle of
around 80º to the normal. Useful for the analysis
of thin coatings, e.g. paints on metallic surfaces.
I
Index of refraction
A property of a material describing the behaviour
of electromagnetic radiation when travelling
through it (not all EM radiation can travel through
all materials). It is defined as being the ratio of
the speed of light in a vacuum to the speed of
light in the material concerned. Also called
refractive index.
Infrared (IR) radiation
The region of the electromagnetic spectrum from
14,000 to 10 cm -1 .
Infrared Spectroscopy
The study of the characteristic Infrared spectra of
matter.
Cont’d
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