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Title: Infrared near-field spectroscopy of trace explosives using an external cavity quantum cascade laser

Utilizing a broadly-tunable external cavity quantum cascade laser for scattering-type scanning near-field optical microscopy (s-SNOM), we measure infrared spectra of explosives particles by probing characteristic nitro-group resonances in the 7.1-7.9 ┬Ám wavelength range. Measurements are presented with spectral resolution of 0.25 cm-1, spatial resolution of 25 nm, <100 attomolar sensitivity, 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:
; ; ; ; ;
Publication Date:
OSTI Identifier:
1130254
Report Number(s):
PNNL-SA-97642
36406
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Optics Express, 21(25):30401-30414
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
(180.4243) Near-field microscopy; (140.5965) Semiconductor lasers, quantum cascade; (160.4890) Organic materials; (310.6628) Subwavelength structures, nanostructures; (240.6490) Spectroscopy, surface; (300.6340); Environmental Molecular Sciences Laboratory