Experts encounter a serious problem when studying the crime scene after an explosion. They can establish to a high degree of probability the type and power of the device used by terrorists and with what explosive substance it was filled with. However, they are usually unable to answer the most important question as to where and when the explosive itself was made: TNT is still TNT, regardless of the where and when it was produced.

Specialists from the Semenov Institute of Chemical Physics and their colleagues from several defense enterprises have developed special encoding additives. If these additives are introduced to the composition of the explosive, the site of the explosion will leave a kind of fingerprint, with which the explosive could be identified and the path of its legal movements could be traced; this would give the investigation into an incident of this kind a thread to uncover the supply channels of the terrorists. This most important work was fulfilled by the researchers in the framework of ISTC Project ¹ 1292.

It is very difficult to make such encoding additives specifically for explosives; the requirements are too strict. On one hand they have to be completely harmless to the product (the explosive) and to the environment in their own right. On the other hand the explosion must not damage the encoding additive. And of course they all have to be individual, to ensure the reliability of the identification process. No dirt or impurities should be able to hinder the recognition of markers or to confuse them.

However, these complications proved no problem to the scientists from the Institute of Chemical Physics. The encoding additives they have proposed to introduce to the composition of explosives do not damage the explosive and are themselves undamaged after an explosion and have no adverse environmental effects.

“These are tiny grains of aluminum alloy, comprised of rare-earth elements,” informs Project Manager and Head of Laboratory Yuri Karasevich. “There are very few such elements in nature and they are dispersed throughout the Earth’s Crust. Therefore, in whatever

whatever quantities they may sensibly be found in special, pre-set combinations, they are not met in either natural or manmade objects. However it will be possible to find them at the site of an explosion; at least if they had been initially introduced to the composition of the explosive.”

Naturally, it is not so simple to identify such “fingerprints” as it is to read information from a barcode in a supermarket. Here the task in fact involves a highly complex chemical analysis of microscopic samples, to discover how many rare-earth elements there are in the sample, what exactly they are and in what combination. And yet the researchers have coped with this most difficult of tasks.

For the analytical method the project authors proposed the use of laser-emission analysis of the element composition, using equipment developed by NPO Typhoon. The scientists also developed the necessary methodology and highly complex software for statistical analysis.

The first tests have already been conducted. Using a special bench in an explosion chamber the properties of an “encoded” explosive were studied and the scientists are confident that it explodes “as it should” – no worse than the explosive in its initial state. The same can be said for the “fingerprints” it leaves, which enable identification to the same level of reliability as a product that is identified by its barcode.