SupressÃo seletiva da luminescÃncia de nanofilmes de complexos de lantanÃdeos induzida por radiaÃÃo UV - n-domo: um dosÃmetro molecular

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

In this work we have developed a new product, a molecular nanofilm, with photonic properties, from which we have developed a dosimetric device for UV radiation, characterized by its unique behaviour, as well as by its selectivity, sensitivity and compactability. The active part of the dosimeter, so called âMolecular Nanodosimetersâ, is composed of a luminescent complex, with the chemical formulae given by [Ln(b-dicetona)3L], Ln=Tb3+ or Eu3+, in which the main ligand is a fluorinated b-diketone, and L is a secondary ligand that avoids water molecules in the first coordination sphere. The thin film, of about tens of nanometers, is produced by thermoevaporation from photonic volatile complexes, or by dispersion of the complex, in the policrystalline powder form, in nitrocellulose-based enamel. The project has associated the fundamental and applied research, up to the design of a prototype, followed by a commercial model, that will fill up an important gap in the area of UV personal dosimetry. The device N-DOMO I, the simplest one, consist of a molecular nanofilm (active part), in which the luminescence degrades irreversibly with the UV radiation dose received, measuring the dose cummulatively, through the memory effect of the luminescence quenching of the complex, in this case, of Eu3+. The response is easily measurable, resulting in numerical absolute measurements when associated to calibration curves. This work has made feasable the development of dosimeters with characteristics that mimetize the human skin regarding the memory effect related to the damage caused by UV radiation and the sensitivity range is compatible with the ones determined by WHO. The dosimeter, also characterized by its compactability and very low cost, can be used in groups of workers that are exposed in their work place, definitively contribuiting for skin cancer prevention and other diseases caused solar UV or artificial sources. The sensitivity of the dosimeter can be determined by the film thickness of the nanofilms produced, for the devices obtained by thermoevaporation, or through the complex quantity for the dispersions in the enamel medium, which has resulted in a new product

ASSUNTO(S)

photonic properties ultraviolet radiation nonofilme molecular propriedades fotÃnicas quimica molecular nanofilm radiaÃÃo ultravioleta

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