The researchers from the University of Michigan have developed recently a laser-based method that could be used in order to detect chemicals such as explosives and dangerous chemicals in an accurate and quick manner. This method could be used in systems that are placed in airports, serving the processes of environmental monitoring, or even in battlefields.

The innovative method combines two techniques that are capable to improve the speed of detection by laser of various dangerous chemicals. The first technique is based on the same idea as nuclear magnetic resonance spectroscopy, using radio frequencies in order to identify the structure of molecules. The method used by the researchers is known as multi-dimensional coherent spectroscopy, which uses ultrashort laser pulses to read types of gases like a bar code. At the moment when the scientists bounce the laser pulses through the mixture of gases, those pulses will be able to “read” the specific wavelengths of light or color that are absorbed by specific gases.

In order to bring a boost to the process, the scientists proceeded in combining this method with another one named dual comb spectroscopy, where the frequency combs are used as laser sources that generate spectra consisting of equally spaced sharp lines that are used as rulers to measure the spectral features of atoms and molecules with extremely high precision. By using two frequency combs, an elegant way to rapidly acquire a high resolution spectrum without mechanical elements will be provided, these ultimately known as “corner cube”. In this “cube”, three mirrors will be arranged in such a way that will make one corner, used to reflect a laser beam directly back on itself.

According to the researchers, this approach could allow the method of multidimensional coherent spectroscopy to escape the lab and be used for practical applications, such as detecting explosives or monitoring atmospheric constituents.

 

Sources:

https://phys.org/news/2017-09-technique-explosives-dangerous-gases-rapidly.html

http://www.ns.umich.edu/new/releases/25123-u-m-researchers-develop-technique-that-could-detect-explosives-dangerous-gases-rapidly-and-remotely