Visible light region

BAPO. The photoinitiator, BAPO, absorbs throughout the UV but also in the long UV and short visible light regions. It has the following structure,... 

PEN is transparent in the visible light region, but can absorb ultraviolet radiation at wavelengths below 380 nm (Figure 10.6). 

In the visible light region, the transparency of neat EVAs increases as the VA content rises. The transparency in the near infrared region is weak and favours heat retention for greenhouse films. 

The ESR spectra of the V-ion-implanted titanium oxide catalysts were measured before and after calcination of the samples in O2 at around 723-823 K, respectively (Fig. 11). Distinct and characteristic reticular V" ions were detected only after calcination at around 723-823 K. It was found that only when a shift in the absorption band toward visible-light regions was observed, the reticular V ions could be detected by ESR. No such reticular V ions or shift in the absorption band have ever been observed with titanium oxides chemically doped with V ions [16,18,19]. 

Differential refractometer-essentially all molecules are detected, but this method is not especially sensitive. Photometric detector—molecules that absorb in the ultraviolet or visible light region. Fluorescence detector-molecules that fluoresce. 

Furthermore, as shown in Fig. 10.2, such red shifts in the absorption band of the metal ion-implanted titanium oxide photocatalysts can be observed for any kind of titanium oxide except amorphous types, the extent of the shift changing from sample to sample. It was also found that such shifts in the absorption band can be observed only after calcination of the metal ion-implanted titanium oxide samples in 02 at around 723-823 K. Therefore, calcination in 02 in combination with metal ion-implantation was found to be instrumental in the shift of the absoiption spectrum toward visible light regions. These results clearly show that shifts in the absorption band of the titanium oxides by metal ion-implantation is a general phenomenon and not a special feature of a certain kind of titanium oxide catalyst. 

Ti ion-implanted titanium oxides exhibited no shift, showing that such a shift is not caused by the high energy implantation process itself, but to some interaction of the transition metal ions with the titanium oxide catalyst. As can be seen in Fig. 10-1 ((b)—(d)), the absorption band of the Cr ion-implanted titanium oxide shifts smoothly to visible light regions, the extent of the red shift depending on the amount and type of metal ions implanted, with the absorption maximum and... 

The carbon cycle is illustrated in Fig. 5.2. All living systems require an external source of energy, either in the form of chemical bond energy, as chemical (redox) potential or as some form of electromagnetic radiation usually in or near the visible light region. 

Vaughan, D. J. (1990) Some contributions of spectral studies in the visible (and near visible) light region to mineralogy. In Absorption Spectroscopy in Mineralogy. (A. Mottana F. Burragato, eds Elsevier Science Publ., Amsterdam), pp. 1-38. 

Kalyanasundaram, K. Vlachopoulos, N. Krishnan, V. Monnier, A. Graetzel, M. Sensitization of Ti02 in the visible light region using zinc porphyrins, J. Phys. Chem. 1987, 91, 2342. 

In the large negative applied voltage, the collection efficiency is nearly equal to unity over the whole visible light region. The lag for this device is 3% after 50 msec and little bum-in is observed (Tsukuda et al., 1981). 

Kikuchi, H., Kitano, M., Takeuchi, M., Matsuoka, M., Anpo, M. and Kamat, P. V. (2006). Extending the photoresponse of Ti02 to the visible light region Photoelectrochemical behavior of Ti02 thin films prepared by the radio frequency magnetron sputtering deposition method. J. Phys. Chem. B 110(11), 5537-5541. 

The analog photography community is well-versed with the fact that silver halides are tunable band gap semiconductors. Thus the photoactivity of AgCl can be tuned from the UV into the visible light region by a process known as self sensitization, which is due to the formation of Ag clusters during the photoreaction. The formation of these clusters introduces new levels within the forbidden gap that can now be populated by visible light (Fig. 7). 

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