A Novel Pulsed Doping Method for Enhancing the Sensitivity of Ion Mobility Spectrum (IMS) for Detecting Explosives and a Mechanism Study

摘要

In this paper, a novel pulsed doping method was developed to enhance the sensitivity of IMS for detecting explosives using hexachloroethane (C_2Cl_6) as the dopant. Conventional doping method of adding dopants constantly to the ionization region of IMS could enhance the sensitivity for some explosives such as Hexogeon (RDX) and Cyclotetramethylene tetranitramine (HMX). However, it would hinder the detection for black powder (BP) and reduce the sensitivity for 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitrotoluene (DNT). The characteristic peaks of RDX and HMX appear much later than TNT, DNT and BP due to their lower gasification speed which was caused by their relatively lower saturation vapor pressure. Based on this difference, the dopant of C_2Cl_6 was added in a pulsed mode to the ionization region to enhance the sensitivity of RDX and HMX after IMS acquiring enough information for accurate detection of TNT, DNT and BP. By optimizing the addition time and amount of the dopant, this pulsed doping method could enhance the sensitivity for RDX and HMX by over 100 times without affecting the detection of TNT, DNT and BP.