157 nm pellicles (thin films) for photolithography: mechanistic investigation of the VUV and UV-C photolysis of fluorocarbons.

The use of 157 nm as the next lower wavelength for photolithography for the production of semiconductors has created a need for transparent and radiation-durable polymers for use in soft pellicles, the polymer films which protect the chip from particle deposition. The most promising materials for pellicles are fluorinated polymers, but currently available fluorinated polymers undergo photodegradation and/or photodarkening upon long term exposure to 157 nm irradiation. To understand the mechanism of the photodegradation and photodarkening of fluorinated polymers, mechanistic studies on the photolysis of liquid model fluorocarbons, including perfluorobutylethyl ether and perfluoro-2H-3-oxa-heptane, were performed employing UV, NMR, FTIR, GC, and GC/MS analyses.

A new approach for the detection of carbon-centered radicals in enzymatic processes using prefluorescent probes.

In this communication we propose a novel application for prefluorescent probes in the detection of free carbon-centered radicals in enzymatic processes. Prefluorescent probes combine a fluorescent moiety tethered to a paramagnetic nitroxide that acts as a fluorescence quencher. Trapping of a radical by the nitroxide group restores the fluorescence properties.