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Introduction
Published in Willy J. Masschelein, Rip G. Rice, Ultraviolet Light in Water and Wastewater Sanitation, 2017
Willy J. Masschelein, Rip G. Rice
The whole range of UV light wavelengths is called actinic waves, also known as chemical waves, in opposition to the thermic waves of a higher frequency. Actinic wavelengths involve energies that are able to provoke direct chemical changes in the irradiated molecules (activation, ionization, dissociation, etc.), and to promote biological changes in the systems accordingly.
Experimental investigation of Effect of Dust Accumulation and Discoloration on Photovoltaic Panel Material
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
The transmittance of a photovoltaic panel superstrate directly affects the electrical performance. Long exposure to a photovoltaic panel can suffer from optical efficiency. Previous studies assumed that short wavelengths of the light spectrum mainly enhance the photo-Fries mechanism of degradation, and hence the long-wavelength limit of this mechanism is about 300 nm. Yellowing and increase in UV absorption of polycarbonate by borosilicate glass filtered xenon arc radiation show two actinic regions: one below 300 nm and the other between about 310 and 340 or 350 nm. Actinism is a property of solar radiation that leads to the production of photochemical and photobiological effects. The shorter wavelengths cause more severe optical changes. However, the photo-Fries rearrangement may occur naturally. The energy balance model and the simulation result of a combined photovoltaic solar thermal system were developed (Malvi, Dixon-Hardy, and Crook 2011). For example, plastic bottles made of polyethylene terephthalate (PET) exposed to direct sunlight, particular to the UV spectrum at a wavelength of about 310 nm, experience photo-Fries rearrangement, as do similar plastic bottles, which are heated to above 40°C even passively in a closed car environment with windows closed on a hot summer day (A, Huraib, and Eugenio 1988; Andrady, Searle, and Crewdson 1992; Czanderna and Pern 1996; Pern 1993, 1996; Pern 1997; Pern, Glick, and Czanderna 1996).