Photosensitive substrates

In these processes poly[bis(4-benzoylphenoxy)phosphazene] has mostly been used as photosensitive substrate because of the triplet state reactivity... 

Photosensitizer Substrate Product Biocatalyst Quantum Yield (9)... 

I. Olenik, M. Kim, A. Rastegar, and Th. Rasing, Alignment of liquid crystals on a photosensitive substrate studied by surface optical second-harmonic generation. Physical Review E 61, R3310 (2000). 

Fig. 1. The hthographic process. A substrate is coated with a photosensitive polymer film called a resist. A mask with transparent and opaque areas directs radiation to preselected regions of the resist film. Depending on resist characteristics, exposed or unexposed portions of the film are removed using a developer solvent. The resulting pattern is then transferred to the substrate surface and the resist is stripped.

Electroless plating on metal substrates can be improved by addition of pentaerythritol, either to a photosensitive composition of a noble metal salt (99), or with glycerine to nickel plating solutions (100). Both resolution and covering power of the electrolyte are improved. 

Other small molecule species decompose and volatilise. The glass frit fuses, wetting the surface of the functional phase, providing adhesion and sealing of the composite to the substrate. Because of the screen printing process, resolution is modest. Fired film thicknesses, which range from 10 to 50 p.m (0.4 to 2.0 mils), are large compared to thin-fHm microelectronics. Some photosensitive pastes are also ia use. 

Amorphous (vitreous) selenium, vacuum-deposited on an aluminum substrate such as a dmm or a plate, was the first photoconductor commercially used in xerography (6). It is highly photosensitive, but only to blue light (2). Its light absorption falls off rather rapidly above 550 nm. Because of the lack of photoresponse in the red or near infrared regions, selenium photoreceptors caimot be used in laser printers having He—Ne lasers (632.8 nm), or soHd-state lasers (680—830 nm). 

Yields of the di- r-methane rearrangement reaction strongly depend on substrate structure, and are ranging from poor to nearly quantitative. Acetone and acetophenone have been used as photosensitizers." ... 

The second direction in which redox properties of sulfones and sulfoxides could manifest themselves in photochemistry is redox photosensitization108,110-114. In such a photosensitization the photosensitizer is transformed by light into a short-lived oxidant or reductant able to react with the substrate to be activated. Tazuke and Kitamura115 have discussed the parameters to play with when one... 

Depending on the relative concentration of reactive substrate and dissolved molecular oxygen ( 02), RF is able to induce photosensitized oxidation of molecular targets by either Type I (electron-transfer) or Type II (energy-transfer) processes (Foote, 1991). In Type I... 

Toyoda T, Kobayashi J, Shen Q (2008) Correlation between crystal growth and photosensitization of nanostructured HO2 electrodes using supporting H substrates by self-assembled CdSe quantum dots. Thin SoUd Films 516 2426-2431... 

Shen Q, Arae D, Toyoda T (2004) Photosensitization of nanostructured TiOa with CdSe quantum dots effects of microstructure and electron transport in HO2 substrates. J Photoch Photobio A 164 75-80... 

Not all sensitized photochemical reactions occur by electronic energy transfer. Schenck<77,78) has proposed that many sensitized photoreactions involve a sensitizer-substrate complex. The nature of this interaction could vary from case to case. At one extreme this interaction could involve a-bond formation and at the other extreme involve loose charge transfer or exciton interaction (exciplex formation). The Schenck mechanism for a photosensitized reaction is illustrated by the following hypothetical reaction ... 

Menadione (79) has been shown by Krishna et al. to act as a photosensitizer for thymine degradation. Spin-trapping experiments with several nucleosides showed that the photosensitizations occurred by electron transfer from the substrate to the excited triplet state of menadione to form the cation radical of the substrate and the anion radical of menadione, both of which were detected... 

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