New laser method helps detect hidden liquid explosives and disease
8 October 2007
A new and powerful technique that can detect hidden liquid explosives
through common plastic containers and glass bottles has been demonstrated by
scientists from the Rutherford Appleton Laboratory (RAL), in Oxfordshire,
The technique, known as 'spatially offset Raman spectroscopy' (SORS) was
originally developed for medical and pharmaceutical applications, but has
now been demonstrated to work in security applications. The technique —
which can be implemented using a hand-held ‘probe’ — produces chemical
information on liquids contained in transparent and diffuse plastic
containers, including those made from coloured materials.
In the Raman
effect, laser light shone on tissue or a substance gives a spectral
signature specific to each chemical present.
SORS enables safe,
non-invasive analysis of human tissue in vivo or the analysis of
chemicals at depths of several millimetres. This is at least an order of
magnitude deeper than that possible with conventional Raman methods.
technology also has potential applications in the detection of adulterated
food products and beverages as well as in quality control in the food,
pharmaceutical and chemical industries.
There is real concern about the
use of liquid explosives by terrorists, which has led to the current
restrictions in place at airports. Current methods for detecting potentially
dangerous materials are time-consuming and not always practical. The
difficulty in detecting these substances is also compounded by the wide
variety of packaging used by air travellers in which these explosives can be
The new technique is reported in the September edition
of Analytical Chemistry (1). "This work is a fine example of how
fundamental scientific research can come up with solutions to practical
problems that concern every one of us," says Professor Mike Dunne, the
Director of the Central Laser Facility at the Rutherford Appleton Laboratory
where the research has taken place.
Dr Pavel Matousek, the project team
leader, commented, "As well as this exciting use in security, this
technology is applicable to a wide range of problems. We are now planning to
develop the technology commercially through a new spin-out company, LiteThru
Ltd, which will address areas such as pharmaceutical manufacture,
anti-counterfeiting and medical diagnosis as well".
1. C Eliasson, NA
Macleod and P Matousek. Non-invasive Detection of Concealed Liquid
Explosives using Raman Spectroscopy. Analytical Chemistry, September
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