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Explosives Detection Breakthrough Via Green Laser
retiarius writes "In keeping with celebrating the USA's
National Chemistry Week (aside from watching the hitcount
for Tom Lehrer's very chemical music video at
CD Baby), I'm duly impressed by an amazingly simple new way to
detect explosives at a distance -- just use a store-bought
presentation green laser pointer and some dimestore
infrared night vision glasses! The (alas, patentable)
details are in
this week's EE Times."
Once debugged (meat), the mfr will probably be able to sell the devices to the govt. If they charge too much, the GSA (procurement) will go out for bids. Local and state bomb squads will have more trouble, but the Federal govt could just give them detectors under some fancy pgm.
The only bomb-sniffing dogs I know are real pussycats. They have the kind of disposition that you trust with the baby, even when the baby is teething and thinks chewing on the dog's ears will help.
"I do not agree with what you say, but I will defend to the death your right to say it"
> I'm sure some of these contain the nitrites you
> mentioned, no?
There is some nitrit included in your list. But please remember, that the absorption and emission wave length not only depend on a single atom or bond but are also greatly influensed by the surrounding bonds/structures.
Your list is nothing but a first indication if the choosen method should be investigated.
They're patenting the creation of such a device (characteristic filters and design) for use as an explosives detector. This is reasonable. As much as patenting a light bulb or a new kind of car engine. A light bulb is just a fancy resistor in a clear vacuum case, right? New LED's are just chemicals stuck between electrode's, right?
This is pretty basic chemistry, and it is quite interesting. My lab does similar stuff in the biomedical/chemical sensing area. We avoid work that involve weapons and things that can become 'projects of the year' (funding that appears and dissapears suddenly).
It is also nice to be able to publish your work, instead of having it classified. I have heard that some people who get into industrially or militarily classified research projects can't publish their work after (I don't know how many people this affects?). This can hamper their prospects for graduation, and means they can't use it as experience for getting other jobs.
Most of those compounds don't even contain nitrogen, let alone nitrites. The closest call would be fertilizer, where there can be nitrites along nitrates.
On the other hand, while nitrites are still allowed as preservatives and colour fixatives in meat products, they should have been banned long ago. Such accidents are unfortunately still pretty common. 1g is usually considered as a fatal dose.
1) This is simple, non-contact method but it relies on a spectral signature general for nitramines and nitro-aromatics. Some chemicals used in parfumery (artificial musk scent) have nitro groups - so there will be false positives.
2) This method will not work for acetonperoxide (the super-unstable explosive prefered by Palestinian suicide bombers and the wannabe shoe-bomber Reid - because acetonperoxide does not contain any nitros) and for fertilizer bombs (no volatile nitroorganics there).
3)Also, this detection method can be fooled by masking the narrow fluorescence signature of nitro explosives by adding other chemicals with broad fluorescence to confuse the instrument into thinking "this is a false positive". All it takes for the bad guys to get hold of the detection device and experiment with some common household, drugstore or paintshop materials to find the right stuff to spray onto their luggage making it immune for this detection. It may well be that a laundry softener or moskyto repellent can threw this techique off.
4) The currently used swab-tests/mass spectrometry analysis at the airports recognize very characteristic ion mass (of the parent molecule and its fragments) - the signal pattern unique for each explosive, so this masspec method is harder to fool and less likely to give false positives.
I doubt that we will ever figure out - and I suspect that even if we did figure out we couldn't do much about it