Bonjour,

Après discution avec Miguel, Yannick et quelques autres personnes des
systèmes de détection utilisés dans les aéroports, on s'est demandé
commen ça fonctionne. Voici ce que j'ai trouvé comme information:

Sur http://www.eudem.vub.ac.be/technologies/technology.asp?tech_id=12
<quote>
The detection of explosives works as follows: a special cloth, or
“swab”, is wiped over the surface of the items in question. It is then
placed into the IONSCAN®, where the particles are heated to the point
where they are turned into vapor. These vapororized substances are then
ionized (given an electric charge) and allowed to “drift” through a
tube. These ions move at different speeds through the tube, depending on
their molecular size and structure. The characteristic speed at which an
ion moves, called ion mobility spectrometry, is a distinct fingerprint
that identifies the original substance. Vapor samples can also be
collected and analyzed. Vapors are collected by drawing them into the
instrument for analysis, where the same procedure as particle analysis
is carried out. The only difference is in how the sample is introduced
into the IONSCAN®.
</quote>

et

<quote>
The Nomadics landmine detector includes an extremely sensitive and
highly selective chemosensor that uses novel amplifying fluorescent
polymers (AFPs) synthesized by research partners at MIT. When vapors of
nitroaromatic compounds such as TNT bind to thin films of the polymers,
the fluorescence of the films decreases. A single molecular binding
event quenches the fluorescence of many polymer repeat units, resulting
in an amplification of the quenching. Analyte binding to the films is
reversible, so the films can be reused.
</quote>

Wikipedia parle en plus de détails sur les ion mobility spectrometer:
http://en.wikipedia.org/wiki/Ion_mobility_spectrometry

Intéressant tout ça.

Cordialement,