title: On the possibility of evanescent wave excitation distal from a solid-liquid interface using light quenching.
abstract: Evanescent wave illumination with total internal reflection is often used to provide excitation near a quartz-water interface. We now show that evanescent illumination at one wavelength and incident angle, coupled with light quenching at a second wavelength and incident angle, can be used for selective excitation of fluorophores located up to 5000 A into the aqueous phase. The displacement of the fluorophore population from the solid-liquid interface depends on the angles of incidence of the excitation and quenching beams and the optical power of the quenching beam. Light quenching with an evanescent wave was demonstrated to be experimentally possible using Pyridine2 and a light-quenching wavelength of 736 nm. The use of combined evanescent wave excitation and evanescent wave quenching could provide selective excitation of fluorophores in the cytoplasmic region of cells and may provide improved response times for optical sensors based on evanescent excitation.
authors.affiliation: Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore 21201-1503, USA. jf@sg.ab.umd.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Lakowicz
authors.forename: Z
authors.initials: Z
authors.lastname: Gryczynski
authors.forename: I
authors.initials: I
authors.lastname: Gryczynski
mesh_terms: D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D010777:Photochemistry / Q000379:methods*; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes