Visible light, penetration

DeLucia EH, Day TA, Vogelmann TC (1992) Ultraviolet-B and visible light penetration into needles of two species of subalpine conifers during foliar development. Plant Cell Environ 15 921-929... 

J. V. Crivello (GE Development and Research Center) The depth of cure that can be achieved by our system depends on a number of factors. Visible light penetrates much... 

The penetration of visible light through foamed polystyrene has been shown to foUow approximately the Beer-Lambert law of light absorption (22). This behavior presumably is characteristic of other ceUular polymers as weU. 

All three techniques probe 500 A to 1 pm or so in depth for opaque materials, depending on the penetration depth of the incident light. For transparent materials, essentially bulk properties are measured by PL and Modulation Spectroscopy. All three techniques can be performed in ambient atmosphere, since visible light is used both as incident probe and signal. 

Radiation curing of epoxies with cationic initiators is well known [20—28]. UV-visible light has been the predominant radiation source the process has been limited to thin coatings due to the low penetration of the visible-UV light [22,23], Thermal and mechanical properties of these materials are low and the curing is incomplete. Several studies have shown that commercially available epoxies with various cationic initiators can be polymerized with EB curing [20,29-34]. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Attacks copper and copper alloys these metals should not be used. Penetrates leather, so contaminated leather shoes and gloves should be destroyed. Attacks aluminum in high concentrations Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization May occur spontaneously in absence of oxygen or on exposure to visible light or excessive heat, violently in the presence of alkali. Pure ACN is subject to polymerization with rapid pressure development. The commercial product is inhibited and not subject to this reaction Inhibitor of Polymerization Methylhydroquinone (35 - 45 ppm). 

Clearly, unless monomer is the intended photoinitiator, it is important to choose an initiator that absorbs in a region of the UV-visible spectrum clear from the absorptions of monomer and other components of the polymerization medium. Ideally, one should choose a monochromatic light source that, is specific for the chromophorc of the photoinitiator or photosensitizer. It is also important in many experiments that the total amount of light absorbed by the sample is small. Otherwise the rate of initiation will vary with the depth of light penetration into the sample. 

Which light penetrates deeper into a natural water body, uv or visible light Why Q 15.11... 

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