Spectroscopic methods make it possible to study molecular specific properties of different materials. The strength of a spectroscopic method lies in its ability to separate one chemical species from a complex surrounding, and to identify it or at least classify it as a hazardous or benign material. To do this, a method needs to have a high degree of molecular specificity. Laser based spectroscopic methods also have the potential to work over long distances. If the intended application is to detect hidden explosives, there are substantial requirements on the sensitivity of the method. This would require the detection of very low amounts of explosives in vapor phase, or very sparse particle residues left on surfaces as a consequence of the handling of explosives. Detection of buried IED's is yet another example of an application that poses extreme requirements concerning detection sensitivity. This technology study gives an overview of some of the most interesting methods currently under development and having a potential ability to be used for standoff detection of explosives trace residues.