Naslov
Electron spin resonance and thermoluminescence for assessment of color changes in irradiated nacres

Autori
Pucić, Irina ; Marušić, Katarina ; Knežević, Željka ; Maltar-Strmečki, Nadica

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
13th Tihany Symposium on Radiation Chemsitry : Porgram and Abstracts / Wojnarowits, Laszlo ; Takcs, Erszebet - Budimpešta, 2015, P64-P64

Skup
Tihany Symposium on Radiation Chemsitry (13 ; 2015)

Mjesto i datum
Balatonalmádi, Mađarska, 29.08.2015. - 03.09.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
cultural heritage ; radiation treatment ; nacre ; color ; termoluminescence ; EPR

Sažetak
Radiation induced color change of nacre that were detected by measurements in CIELAB color space are likely to be caused both by color centers arising of electronic excited states and/or unpaired electrons in free radicals produced by high-energy irradiation. Nacre or mother-of- pearl, a common ornament material in cultural heritage (CH) objects is a natural biocomposite based on crystalline calcium carbonate, predominately in aragonite form. Two different nacre types, one white and the other yellowish, obtained from Museum of Arts and Crafts in Zagreb were irradiated to various doses in the range commonly applied in CH treatment. The goal of this research was to identify the nature of color centers formed upon irradiation of nacre. Electron spin resonance (ESR) was used to detect and identify species containing unpaired electrons Thermoluminscence (TL) provided information on trapped electrons and holes since on heating trapped states rapidly decay into lower-energy states with emission of photons. Even for unirradiated nacres both TL and ESR results were significantly different. Strong signals of Mn in various ESR-active states were observed in white nacre but not in brownish one. In irradiated brownish nacre TL signal intensities and maximum temperatures changed in an unexpected way. The TL response of white nacre was more regular with some changes in the shape of spectra at the doses over 6 kGy. ESR signals of carbonate and radicals were detected in both nacres, the signal increased with dose but there were some variations revealing inhomogeneity of nacre.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija, Kemijsko inženjerstvo

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