Water threshold wavelength

Figure 3. Plot showing the variation of solar energy conversion efficiency with threshold wavelengths at sea level. The solid vertical lines represent the energies required for decomposition of water using one or two photons per molecule of water respectively (4 photons would be at 2000 nm). The dashed vertical lines represent computed values for these threshold wavelengths taking into account unavoidable thermodynamic losses (adapted from ref. 8)...

Adsorption of substrates may also be altered by photoexcitation or by the presence of other adsorbates. That adsorption and photoadsorption are influenced by thermal removal of water and surface hydroxyl groups has been shown in detailed studies On tin oxide, preadsorption of other reagents can produce a substantial increase in oxygen photoadsorption under sub-band gap irradiation and can shift the photosensitivity threshold to longer wavelengths... 

The spectral dependence of the light sensitivity (as indicated by yellowing) of free films of Parylene-C was determined. A Heraeus Sun-Test chamber, equipped with a xenon arc lamp filtered to yield a simulated solar spectrum, was used for the irradiation. An additional infrared filter minimized sample heating. The irradiance at the sample location was originally 0.83 W/m2 at 340 nm, but the output decreased approximately 20% after 1500 hours use. Long band-pass optical filters with nominal cut-offs of 305 nm, 345 nm, 385 nm and 400 nm were inserted between the xenon lamp and the Parylene-C film samples to determine the wavelength threshold for yellowing. The sample temperature was maintained at 30+ 2 °C with a water-cooled... 

The/ frequency dependence is consistent with experimental observations reported in Elrod et al. [5] for which a least-squares fit provides a dependence of the form Typical magnitudes for water droplet ejection using a 5 MHz focused beam include a drop of approximately one wavelength in diameter (A, 300 pm) and a threshold energy in the range of tens of microjoules [5]. Interestingly, most of the energy in the wave is reflected as... 

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