title: [Ultrasensitive analysis of R6G and R110 in solution].
abstract: This paper describes the ultrasensitive detection of R6G and R110 in a flowing aqueous sample, based on laser-induced fluorescence (LIF) combined with mode-locked pulsed excitation and time-correlated single-photon counting. A high repetition rate mode-locked argon ion laser operated at 514.5 nm was used as the excitation source. The laser beam was found tightly into a thin wall capillary flow cell. The probe volume was about 12.6 x 10(-12)L. Fluorescence was collected at 90 degrees using a x 40 microscope objective, and was detected by a fast response PMT detector. A time-gate was used to discriminate Raman scattering light background. Using the criterion of 3 standard deviations above background, the detection limits obtained for R6G and R110 were 3.8 x 10(-14) mol/L and 1 x 10(-13) mol/L respectively, and the average probability was lower than 1 in the presence of a R6G or a R110 molecule in the detection volume.
authors.affiliation: Department of Modern Applied Physics, Center of Atomic and Molecular Sciences, Tsinghua University, 100084 Beijing.
authors.forename: W
authors.initials: W
authors.lastname: Ma
authors.forename: J
authors.initials: J
authors.lastname: Xiong
authors.forename: J
authors.initials: J
authors.lastname: Wei
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Wen
authors.forename: D
authors.initials: D
authors.lastname: Chen
mesh_terms: D007834:Lasers; D012235:Rhodamines / Q000032:analysis*; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: D012235:Rhodamines; D012996:Solutions; C026188:rhodamine 6G; D014867:Water; C049025:rhodamine 110