Fig 1
Ozone layer depletion on the west coast of South America, map of stratospheric ozone distribution obtained from NASA (Jan 31st, 2005). Notice the depletion of the ozone layer over the west coast FO South America.
Context in source publication
Context 1
... being on the west coast of South America, is exposed to an increase of UV radiation during the summer as a result of the presence of a stratospheric ozone layer depletion which runs the length of Chile as can be appreci- ated in fig. 1 (see [1]). UVB irradiance values during the summer and winter solstice of 2006 were 33.3 µW/m 2 and 6.2 µW/m 2 , respectively. For more detailed UV climatology information on Valparaíso see [2]. The city of Valparaíso is surrounded by an extensive forest area and is prone to forest wildfires during the summer months. Wildfires dam- ...
Citations
The photoacoustic effect, produced by the F-center in alkali halide crystals, is analyzed using the configuration coordinate model. By using the configuration coordinate model it is possible to explain the temperature increase of the sample when the sample is illuminated and the F-centers absorb light. Also this model explains the piston effect upon the atmosphere that surrounds the sample when the sample is illuminated. The temperature increase and the piston effect, produced during the development of the photoacoustic effect, cause the sound wave generation in the atmosphere that surrounds the sample when the F-centers absorb light. Using this model, the temperature increase value for a KCl sample and the displacement of the faces of the crystal during the process for the following crystals: KCl, KBr, KI and NaCl, have been determined.
The common photoacoustic spectrum (PAS) is wider than the optical absorption spectrum in KCl crystals. A photoacoustic experiment was performed with a solid KCl sample that was additively colored according to the Van Doorn technique. The sample had about 10(17) [F/cm(3)]. It was determined that the PAS is composed of many bands of the F and aggregate centers. It is explained here, using the configuration coordinate model, that the photoacoustic effect in alkali halides with F-centers shows experimental broadening of the photoacoustic band relative to the F -band. Furthermore, experimental data is added resolving the photoacoustic bands of the agglomerates and also the bands of higher excited states of the F-center. Finally, assuming a configuration coordinate model and the F-centers as sources of heat, an estimation is made for the increase of the sample temperature.
A correlation between the photoacoustic (PA) and optical absorption (OA) spectra of X-irradiated NaCl:Y crystals is reported. The F-band spectra observed through PA spectroscopy is found to be sharper than that of OA spectroscopy. This sharpening is attributed to the reduced probability of nonradiative decay processess of F-Centres over the radiative processes. Two bands observed in the UV region of both the spectra are attributed to the Y+ impurity transitions in the host matrix.
