APR Nov/Dec 2022 - 33

« SPECTROSCOPY
gasoline, chemicals, and plastics. It makes
use of a specific formula or recipe to create
a product from a combination of ingredients
or raw materials, involving numerous checks
throughout the entire process, starting by
establishing the quality of the raw materials
and intermediate compounds, all the way
through to testing the purity of the end
product. The process analytical technologies
(PATs) used for this purpose must be accurate
and reliable, as well as adaptable, as they
will be employed at different manufacturing
stages. An example of a technology that
is flexible enough to be used for process
production is Raman spectroscopy.
Raman spectroscopy is a powerful analytical
tool that provides rapid and precise analysis
without being destructive to the sample.
It has significant advantages over other
spectroscopic methods, such as infrared (IR)
and near-infrared (NIR) spectroscopy, as it
offers specificity, compatibility with aqueous
systems, and sampling flexibility, making it
the method of choice for process monitoring.
Identifying Molecules
Raman
spectroscopy
Small Footprint,
Large Impact
Raman technology is non-destructive,
which makes it ideal for continuous process
monitoring with in-line or on-line analysis. It
can be integrated directly into a production
line and delivers results in a manner of
seconds. The downside is that, up until now,
this technique has demanded complex,
bulky and expensive equipment, as well
as a specialist technician to operate and
maintain the instrument. These requirements
compromised the reliability of this approach
and increased the operational costs. The
introduction of compact, easy-to-use, reliable
and affordable systems changed the Raman
technology landscape, making it accessible
to a wider public. These new devices are
not only smaller but also designed with less
experienced operators in mind, offering
helps extract
information about the chemical structure,
phase and polymorphy,
crystallinity and
molecular interactions by observing how
laser light interacts with the matter. The laser
beam is delivered to the sample using a fiberoptic
cable with a probe at its end, and the
incoming energy causes the molecules to
vibrate and scatter the light, which is collected
and interpreted by a detector. The scattering
can be either elastic, with the energy of the
molecule unchanged after interaction with
the photon, or inelastic, where the molecule
absorbs some of the energy and the scattered
photon loses energy, resulting in a color
change. The latter process is important as
it provides valuable insight regarding the
molecules present, generating a so-called
Raman spectrum - a collection of peaks at
certain photon frequencies that is unique
to each molecule and can be used as a
fingerprint to identify it. In this manner, it is
not only possible to identify which molecules
are present, but also in which amounts.
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APR Nov/Dec 2022

Table of Contents for the Digital Edition of APR Nov/Dec 2022
