title: Absorption measurements in liquid core waveguides using cavity ring-down spectroscopy.
abstract: Short liquid core waveguides (LCWs) were included into a fiber-loop cavity ring-down absorption spectrometer to reduce the detection limit over, both, single pass absorption in a LCW and cavity-enhanced absorption using a conventional fiber-loop cavity. LCWs of 5 and 10 cm length were interfaced with a pressure-flow system and a multimode fiber-loop cavity using concave fiber lenses with matching numerical apertures and diameters. Two red dyes, Allura Red AC and Congo Red, were detected with a 532 nm pulsed laser at a 5 nM limit of detection in a detection volume of less than 1 μL, corresponding to a minimal detectable absorbance of less than 4 × 10(-4) cm(-1) and a minimal detectable change in absorption cross section, σ(min) = V(det) × ε × C(LOD), of about 14 μm(2) (Allura Red AC) and 37 μm(2) (Congo Red).
authors.affiliation: Department of Chemistry, Queen's University, Kingston, ON, Canada.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bescherer
authors.forename: Jack A
authors.initials: JA
authors.lastname: Barnes
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Loock
mesh_terms: D003035:Cobalt / Q000032:analysis*; D004247:DNA / Q000032:analysis*; D005296:Ferrous Compounds / Q000737:chemistry*; D007834:Lasers; D009930:Organic Chemicals / Q000032:analysis*; D011196:Potassium Permanganate / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D005296:Ferrous Compounds; D009930:Organic Chemicals; D011196:Potassium Permanganate; D003035:Cobalt; D012822:Silicon Dioxide; D004247:DNA; C018021:cobaltous chloride