Strong enhancement of optical absorbance from ionic self-assembled multilayer thin films of nanocluster Pt and polymer dye

Abstract

The observation of unusually enhanced optical absorbance spectra of ionic self assembled multilayer (ISAM) thin films composed of alternating layers of Pt nanoclusters (<1 nm dimension) and polymer dye is reported. The first bilayer absorbance is found to be considerably larger than that of several succeeding bilayers even though there is no difference in composition for each bilayer. A layer-by-layer-dependent redshift in maximum wavelength position due to the strong coupling of metals and polymer molecules is observed. The saturation absorption is obtained for the first time when the required thickness of the ISAM film is deposited. The large and unusual enhancement effects are attributed to both the charge-transfer mechanism and very large local fields and collective phenomena near the surface of the small metal clusters/electrolytes and at the interfaces between the cluster/polymer multilayers.

Ultraviolet radiation detection by barium titanate thin films grown by sol–gel hydrothermal method

“…The rough surface of nanostructured metals can induce large scattering of photons and increase the absorption in semiconductor [24] as observed in the present case. The obtained results clearly highlight the importance of the presence of W modifier over the surface of BTO thin film for increasing the absorption of UV photons for both PD-2 and PD-3 photodetectors.…”

Thermal cycling and the optical and electrical characterization of self-assembled multilayer Nile Blue A–gold thin films

“…The bilayers provide the individual dye molecules with direct contact to gold nanoparticles, giving a greatly increased absorbance owing to surfaceenhancement phenomena. 3 The absorption enhancement is due to a charge-transfer mechanism where by electronic excitation may be transferred between the dye molecule and the metallic nanocluster. As more bilayers are built, a slight redshift in maximum absorbance is observed, indicating a greater number of charge transfers through the ionic bands of the dye molecules and gold nanoclusters.…”

“…2 Further studies indicated that such films show an enhancement of optical absorption at specific wavelengths owing to a strong resonance interaction between the metallic nanoparticles and the dye molecules. 3 Widely different electrodeposition techniques have been used to construct oligothiophenelinked metallic nanoparticles by use of organic bridging molecules. 4,5 Additionally, polystyrene spheres have been used as templates for metallic nanoparticle adsorption, making it possible to tune the optical properties of a film by controlling particle sizes and densities.…”

Optical Fiber Logging System for Multiphase Profile Analysis in Steam Injection Wells

“…The optical fiber sensor system operates based on a variation of the modal domain concept discussed in prior publications [6][7][8][9][10][11]. By exposing the optical fiber to the flowing multiphase field, and performing required signal processing on the output two-dimensional speckle interference signal, measurements that allow discrimination of multiple flowing material phases and their flow rates may be determined.…”