INFRARED SPECTROSCOPY *INSTRUMENTATION*

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INFRARED SPECTROSCOPYINSTRUMENTATION

• By
• Maria Ailyn L. Bancale
• Johanna C. Claro
• Helen K. Magdaraog

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(No Transcript)
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What are the tires of your car and the soles of
your shoes made of ? If you thought of rubber,
you were thinking of one of many products that
would not exist as it does today without
infrared spectroscopy. Infrared (IR)
spectroscopy is a way to measure characteristic
vibrations of molecules, making it one of
the most popular techniques in chemistry for the
last 45 years. Infrared spectroscopy entered
into widespread use after the government
utilized the technique with great success for
large-scale production of synthetic rubber
during World War II.
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Introduction to Infrared Spectroscopy

• Infrared spectroscopy measures the vibrations of
  molecules. Each functional group, or structural
  characteristic, of a molecule has a unique
  vibrational frequency that can be used to
  determine what functional groups are in a sample.
  When the effects of all the different functional
  groups are taken together, the result is a unique
  molecular "fingerprint" that can be used to
  confirm the identity of a sample.

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Butadiene was the essential chemical ingredient
of the synthetic rubber program during World War
II. Butadiene molecules were linked in long
polymer chains to produce synthetic rubber.
Knowing the concentration and purity of butadiene
was essential to controlling rubber quality, and
infrared spectroscopy was the only technique that
could accurately gauge these properties. Finding
the concentration and purity of hydrocarbons is
only the very tip of what infrared spectroscopy
can do. Because of its versatility and
convenience, IR spectroscopy is now an essential
in almost every branch of chemistry.
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Landmark Instrument Perkin-Elmer 21
The Perkin-Elmer 21 was the first commercially
successful dual-beam infrared spectrometer. Its
introduction came after several technological
hurdles, but the PE 21 allowed scientists to
take high resolution IR spectra quickly and
reproducibly for the first time, ushering in a
new era in chemical analysis and identification.
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The dual-beam system and chart recorder of the
Perkin-Elmer 21 made infrared spectrometry a
viable method for chemical analysis. Compared to
the single-beam optics and cantankerous behavior
of the PE 12, its predecessor, the PE 21 was
revolutionary. With the introduction of Fourier
Transform IR spectrometry (FT-IR), IR instruments
were suddenly able to produce better spectra in
less time than ever before. This technology, as
well as a few other improvements, are found in
almost every modern IR instrument.
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Perkin-Elmer 21 IR Spectrophotometer
http//orgchem.colorado.edu/hndbksupport/irtutor/t
utorial.html
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How Instrument works? The Perkin-Elmer 21
Infrared spectrometer
The Perkin-Elmer 21 Infrared spectrometer was the
first infrared instrument to use a dual-beam
optical system. In a dual beam infrared
instrument, the infrared beam is split using
mirrors to make two beams. One of the beams goes
through a blank, or reference, cell while the
other beam goes through the sample. The beams
are read in fast succession by the detector and
the signal from the reference beam is subtracted
from the sample beam, resulting in a much more
precise spectrum in a shorter amount of
time. The dual beam design of the PE 21 avoided
many of the problems that kept its predecessor,
the Perkin-Elmer 12, from being a tool worth
using by non-spectroscopists. With the advent of
the PE 21, infrared spectroscopy became a tool
for chemists of all disciplines, particularly
organic and polymer chemistry.
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How Instruments work?Modern IR Spectrophotometry
Modern infrared spectrometers are very different
from the early dispersive instruments that were
introduced in the 1940s. While there is still a
need for dual-beam dispersive instruments in
high-precision work, most instruments today use
a Fourier Transform infrared (FT-IR) system.A
Fourier transform is a mathematical operation
used to translate a complex curve into its
component curves. In a Fourier transform
infrared instrument, the complex curve is an
interferogram, or the sum of the constructive and
destructive interferences generated by
overlapping light waves, and the component curves
are the infrared spectrum.
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The standard infrared spectrum is calculated from
the Fourier-transformed interferogram, giving a
spectrum in percent transmittance (T) vs. light
frequency (cm-1). An interferogram is generated
because of the unique optics of an FT-IR
instrument. The key components are a moveable
mirror and beam splitter. The moveable mirror is
responsible for the quality of the
interferogram, and it is very important to move
the mirror at constant speed. For this reason,
the moveable mirror is often the most
expensive component of an FT-IR spectrometer. The
beam splitter is just a piece of semi-reflective
material,
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usually mylar film sandwiched between two pieces
of IR-transparent material. The beam splitter
splits the IR beam 50/50 to the fixed and
moveable mirrors, and then recombines the beams
after being reflected at each mirror.
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Spectrophotometry is the quantitative study of
electromagnetic spectra It is more specific than
the general term electromagnetic spectroscopy in
that spectrophotometry deals with visible light,
near-ultraviolet, and near-infrared. Also, the
term does not cover time-resolved spectroscopic
techniques.
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Spectrophotometry involves the use of a
spectrophotometer. A spectrophotometer is a
photometer (a device for measuring light
intensity) that can measure intensity as a
function of the color,or more specifically, the
wavelength of light.There are many kinds of
spectrophotometers. Among the most important
distinctions used to classify them are the
wavelengths they work with, the measurement
techniques they use, how they acquire a spectrum,
and the sources of intensity variation they are
designed to measure. Other important features of
spectrophotometers include the spectral bandwidth
and linear range.
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Spectrophotometer
http//en.wikipedia.org/wiki/Spectrophotometer
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Comprised of 4 models, RT8A series is built to
withstand demands of measuring temperature of
moving materials, webs, or inaccessible objects
in hostile production environments. Non-contact,
2-wire instruments cover operating temperatures
from 0 to 1,000F and are protected by NEMA 4X
housing, which can be supplemented by optional
cooling and lens purging facilities. Response
time is adjustable from 1-10 sec, and accuracy is
less than 0.5 of span.
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New Rugged Infrared Thermometer Takes Everyday
Knocks in the Production LineThe new RT8A
infrared thermometer from Land Instruments
International is sturdily built to withstand the
rigours of measuring the temperature of moving
materials, webs or inaccessible objects without
contact in hostile production environments.Measu
ring product temperature in this way can improve
quality, conserve energy, and optimise production
rates without contaminating, damaging or
interfering with the process or material.
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Encompassing four models covering operating
temperatures from 0 to 500C/0 to 1,000F, the
two wire stand-alone RT8A range of infrared
thermometers is suitable for a wide variety of
primary OEM and end-user applications in
industries as diverse as asphalt, mineral
processing, glass, food, paper, converting,
plastics, printing and textiles.
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The environmental protection provided by the
rugged, NEMA 4X/IP65 rated housing can be
supplemented by optional cooling and lens
purging facilities when required to provide two
levels of protection from the hazards of hostile
environments.A comprehensive choice of mounting
and protection accessories from the well-proven
System 4 range makes it easy to install the
thermometer at the optimum point in the process.
Wiring connections are simple to make, and no
tools are required to access the protected
thermometer.
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RT8A thermometers are designed to be integrated
directly into a simple two-wire 4 to 20mA
current loop for measuring, monitoring or
control purposes.Accurate, reliable and stable
temperature measurement is assured by the RT8A's
response time, which is adjustable from 1 to
10s accuracy within lt0.5 of spanand minimal
drift with change in ambient temperature of
1.5C per 10C. http//news.thomasnet.com/fullst
ory/483674/rss
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IR Thermometer