Near-field scanning optical microscopy and polymers

Abstract Polymer composite films consisting of fluorescent nanometric particles of dye-labeled latex dispersed in poly(vinyl alcohol) matrices were imaged with an aperture Near-field Scanning Optical Microscope (NSOM). Different films of this type with a thickness of ∼ 25 nm containing latex particles with diameters of 103 nm ± 9 nm or of 14 nm ± 3.7 nm with low particle density were studied. During image acquisition with the NSOM the particles were excited by a tunable argon ion laser. In case of the 103 nm small particles the excitation wavelength, λ, was chosen to be at the maximum or at the red edge of the excitation band at λ = 458 nm or at λ = 488 nm, respectively. In case of the 14 nm small particles the respective films were excited at λ = 488 nm. In both cases strong fluorescence spots with FWHM diameters of λ 2 could be found. Additionally, photobleaching of a single 103 nm small fluorescent latex particle with a NSOM was performed representing a controlled photochemical reaction on a submicrometer length scale. Beside the presentation of the own work, references to the application of near-field optical microscopy to the investigation of thin polymer films are given.