Spectroscopic investigations on the depth-dependent degradation gradients of aged triterpenoid varnishes

Theodorakopoulos, Charis, Zafiropulos, Vassilis, Boon, Jaap and Boyatzis, Stamatis (2007) Spectroscopic investigations on the depth-dependent degradation gradients of aged triterpenoid varnishes. Applied Spectroscopy, 61 (10). pp. 1045-1051. ISSN 0096-8706

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Abstract

The depth-profiles of accelerated aged triterpenoid dammar and mastic varnishes, which had been uncovered by optimized KrF excimer laser ablation (248 nm, 25 ns), were examined by ultraviolet-visible (UV/VIS) spectrophotometry and attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy. The results reflect both the optical properties at the bulk (UV/VIS) and the surface (ATR/FT-IR) and establish the presence of degradation gradients across the depth of the degraded natural resin films. It is demonstrated that the UV part of the ambient radiation is absorbed by the deteriorated surface and that the optical densities of the aged varnish decrease as a function of depth. The absorbed UV wavelengths at the surface and the depth-wise reduction of light intensity result in a depth-dependent decrease in carbonyl absorbance and an increase in C-H bending vibration modes of methylene species pointing to structural modification in the triterpenoid mixture across depth.

Item Type:	Article
Subjects:	F100 Chemistry F300 Physics W100 Fine Art
Department:	Faculties > Arts, Design and Social Sciences > Arts
Depositing User:	Dr Charis Theodorakopoulos
Date Deposited:	25 Oct 2013 13:41
Last Modified:	12 Oct 2019 19:42
URI:	http://nrl.northumbria.ac.uk/id/eprint/14395

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