title: Infrared near-field spectroscopy of trace explosives using an external cavity quantum cascade laser.
abstract: Utilizing a broadly-tunable external cavity quantum cascade laser for scattering-type scanning near-field optical microscopy (s-SNOM), we measure infrared spectra of particles of explosives by probing characteristic nitro-group resonances in the 7.1-7.9 µm wavelength range. Measurements are presented with spectral resolution of 0.25 cm(-1), spatial resolution of 25 nm, sensitivity better than 100 attomoles, and at a rapid acquisition time of 90 s per spectrum. We demonstrate high reproducibility of the acquired s-SNOM spectra with very high signal-to-noise ratios and relative noise of <0.02 in self-homodyne detection.
authors: Ian M
authors: IM
authors: Craig
authors: Matthew S
authors: MS
authors: Taubman
authors: A Scott
authors: AS
authors: Lea
authors: Mark C
authors: MC
authors: Phillips
authors: Erik E
authors: EE
authors: Josberger
authors: Markus B
authors: MB
authors: Raschke
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D053834:Explosive Agents / Q000032:analysis*; D007834:Lasers; D008832:Microchemistry / Q000295:instrumentation*; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation*; D014159:Transducers
chemical_list: D053834:Explosive Agents