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The LIF and LIPS spectroscopy for diagnostics and monitoring of the laser cleaning of historical paper documents
Języki publikacji
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Techniques of laser induced spectroscopy: LIF and LIPS for diagnostics and monitoring of laser cleaning of old paper documents are proposed and experimental examples of applications are discussed. The LIF spectra of the model and historical paper samples are recorded under different conditions, i.e. pulsed excitation at 266 nm and 532 nm (fourth and second harmonic of Nd:YAG laser), and at the cryogenic (10K) and room temperature, before and after cleaning by means of the laser (532 nm, 0.5 J/cm/} or by the chemical method. The presence of contamination reveals a marked effect on the spectra which also depend strongly on the sample cleaning history. For excitation at 266 mn the characteristic band structure of the paper is observed in the LIF spectra in agreement with previous experiments. Results of the LIPS monitoring of laser cleaning (532 nm, 0.5 J/cm2) of an archive book from XIX cent, covered by a dark, dust-like layer of contamination confirms the usefulness of the applied diagnostic method. Sharp emission lines recorded at 589.4, 616.4, 780 nm (Na I); 612.5, 644.2, 646.5, 649.7, 671, 714.9, 720.2 nm (Ca I); and 766.5, 769.9 nm (Mg I) are ascribed to the surface pollutants and their intensity decrease with successive pulses. The broad band centred at 616 nm, originates most probably from the substrate fluorescence with superimposed contamination peaks.
Rocznik
Tom
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139--156
Opis fizyczny
Bibliogr. 13 poz.
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Bibliografia
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Bibliografia
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bwmeta1.element.baztech-1f824eca-4db0-4bc0-aeb9-71914bc542f3