title: Deep Raman spectroscopy for the non-invasive standoff detection of concealed chemical threat agents.
abstract: Deep Raman spectroscopy has been utilized for the standoff detection of concealed chemical threat agents from a distance of 15 m under real life background illumination conditions. By using combined time and space resolved measurements, various explosive precursors hidden in opaque plastic containers were identified non-invasively. Our results confirm that combined time and space resolved Raman spectroscopy leads to higher selectivity towards the sub-layer over the surface layer as well as enhanced rejection of fluorescence from the container surface when compared to standoff spatially offset Raman spectroscopy. Raman spectra that have minimal interference from the packaging material and good signal-to-noise ratio were acquired within 5 s of measurement time. A new combined time and space resolved Raman spectrometer has been designed with nanosecond laser excitation and gated detection, making it of lower cost and complexity than picosecond-based laboratory systems.
authors.affiliation: Nanotechnology and Molecular Sciences Discipline, Science and Engineering, Queensland University of Technology, 2 George St., Brisbane QLD 4001, Australia. e.kiriakous@qut.edu.au
authors.forename: Emad L
authors.initials: EL
authors.lastname: Izake
authors.forename: Biju
authors.initials: B
authors.lastname: Cletus
authors.forename: William
authors.initials: W
authors.lastname: Olds
authors.forename: Shankaran
authors.initials: S
authors.lastname: Sundarajoo
authors.forename: Peter M
authors.initials: PM
authors.lastname: Fredericks
authors.forename: Esa
authors.initials: E
authors.lastname: Jaatinen
mesh_terms: D001466:Barium Sulfate / Q000032:analysis*; D002619:Chemical Warfare Agents / Q000032:analysis*; D053834:Explosive Agents / Q000032:analysis*; D006801:Humans; D007834:Lasers; D008697:Methane / Q000031:analogs & derivatives* / Q000032:analysis; D009566:Nitrates / Q000032:analysis*; D009595:Nitroparaffins / Q000032:analysis*; D059629:Signal-To-Noise Ratio; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013997:Time Factors
chemical_list: D002619:Chemical Warfare Agents; D053834:Explosive Agents; D009566:Nitrates; D009595:Nitroparaffins; D001466:Barium Sulfate; D008697:Methane; C008640:nitromethane; C006568:ammonium nitrate