Substrates, optical absorbances

A breakthrough came in 1988 when Hamada et al. demonstrated that a dye layer with a relatively low optical absorbance and high reflectance at the recording wavelength could be interposed between the substrate and reflecting layer of a CD-ROM type structure, and, with appropriate optimization of the optical properties, this would record and reproduce in accordance... 

Figure 47, SAMPLE generated profile simulations in AZ1350J resist exposed at 436 nm on an index matched substrate. The mask edge is at 0.75um on the horizontal scale. The unbleachable optical absorbance (A) was varied from the actual value at 436 nm, 0.08 to 0.43. The dose was adjusted to develop each case to dimension (l.5um space) at constant development time. As A increases, all other factors being constant, the dose required to open the line increases and the resist profile becomes...

Table IV. Optical Absorbances of Substrates at Selected Wavelengths by Diffuse Reflectance3...

Thickness Determinations in Laminar Systems. From now on, all samples will be assumed to be laterally uniform. The simplest characterization task is to determine the thickness of films where the dielectric properties of the films and substrates are already known. Data from single-wavelength ellipsometers can be used to solve model equations for thicknesses of transparent films, modulo a repeat thickness X/2n, with submonolayer sensitivities (7.). If the films are more than about 100A thick, then both thickness and refractive index can be obtained. However, too many unknowns are involved if the films are optically absorbing, and for very thin films the results are extremely sensitive to the exact values of the dielectric properties of the substrate and interface. Also, no cross-check is obtained on the reliability of the solution. 

The present study aims to understand the influence of solvent quality on the molecular-level friction mechanism of tethered, brushlike polymers. It involves complementary adsorption studies of PLL-,g-PEG by means of optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microbalance with dissipation (QCM-D) as well as friction studies performed on the nanoscale using colloidal-probe lateral force microscopy (LFM). The adsorbed mass measured by QGM-D includes a contribution from solvent molecules absorbed within the surface-bound polymer fllm. This is in contrast to optical techniques, such as OWLS, which are sensitive only to the dry mass of a polymer adsorbed onto the surface of the waveguide.By subtracting the dry mass , derived from OWLS measurements, from the wet mass , derived from QCM-D measurements, it is therefore possible to determine the mass of the solvent per unit substrate area absorbed in the brushlike structure of PLL- -PEG, expressed as areal solvation, P. Areal solvation was varied by choosing solvents (aqueous buffer solution, methanol, ethanol, and 2-propanol) of different quality with respect to the PEG brush. The solvents were characterized in terms of the three-component Hansen solubility parameters, and these values were compared with measured areal solvation of the PEG brush. 

The ABC film was prepared from amphiphilic dye p-nonyl-amino-p -carboxyazobenzene whose molecule contains an azobenzene chromophore, a polar head (-COOH) with electron acceptor properties and hydrophobic tail (-NHC9H19) with electron donor properties. In this work, as earlier [12], we used an X-type LB film consisting of 30 monolayers transferred onto an ITO covered glass substrate by the Schafer technique at surface pressure 3-5 mN/m. The thiekness of the film estimated from the optical absorbance at A,=460nm and by AFM measurements is 40nm. 

Figure 5.5 LSPR detection schemes, (a) nanoparticle assay and (b) nanoparticle substrate. Usually, the incident light is a white light the optical absorbance spectra through the particles before and after analyte interaction are measured.

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