[Ultrasensitive analysis of R6G and R110 in solution].
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.
Ma
W
W
Department of Modern Applied Physics, Center of Atomic and Molecular Sciences, Tsinghua University, 100084 Beijing.
Xiong
J
J
Wei
J
J
Zhang
L
L
Liu
G
G
Wang
S
S
Wen
K
K
Chen
D
D
D007834:Lasers; D012235:Rhodamines / Q000032:analysis*; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
D012235:Rhodamines; D012996:Solutions; C026188:rhodamine 6G; D014867:Water; C049025:rhodamine 110