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A modified and improved photografting procedure of Topas® surface hydrophilization is investigated in order to obtain stable modification of the polymer for long term storage. The achieved hydrophilicity and monitoring of the wettability during one month of storage are presented as well as a description of the optimal cleaning procedure and storage conditions to maintain the modified surface. Three minutes of oxygen plasma activation followed by 4 min of acrylic acid UV-photografting at 50 °C leads to the most stable hydrophilicity that was characterized by an initial water contact angle of 53.5° ± 1.2°. Storage of the modified material in cold water at 4 °C and refraining from ultrasonic cleaning limit water contact angle increase to 5° over 30 days. In comparison with pristine hydrophobic Topas, the proposed treatment improves chromosome spreading ability significantly.

Silicon-rich nitride, deposited by LPCVD, is a low stress amorphous material with a high refractive index. After deposition the silicon-rich nitride thin film is annealed at temperatures above 1100 °C to break N H bonds, which have absorption peaks in the wavelength band important for optical telecommunication. However, silicon clustering appears in the thin films when annealing above 1150 °C. Clustering is undesirable in waveguide materials because the localized variations of the refractive index associated with the clusters lead to Raleigh scattering, which can cause significant propagation loss in optical waveguides. This means that the annealing temperature must be high enough to break the N H bonds, but no so high as to produce clusters. Therefore, the process window for an annealing step lies between 1100 and 1150 °C. The chemical composition of amorphous silicon-rich nitride has been investigated by Rutherford back scattering (RBS) and X-ray photoelectron spectroscopy (XPS). The influence of deposition parameters and annealing temperatures on the stoichiometry and the chemical bonds will be discussed. The origin of the clusters has been found to be silicon due to severe silicon out-diffusion from the substrate during annealing at temperatures above 1100 °C.

The deposition rate of laser-ablated silver has been determined for fluences between 0.5 and 15 J / cm 2 at the wavelengths 532 and 355 nm for a beam spot area of around 0.01 cm 2 . The ablated metal was collected on a quartz crystal microbalance. The rate at 5 J / cm 2 was about 4 x 10 13 Ag / cm 2 per pulse for 532 nm, and somewhat lower for 355 nm. The initial vaporization during the ablation has been studied numerically as well.