I. A. Balakhnina

Optoacoustic measurements of the porosity of paper samples with foxings

The goal of this work is to investigate the porosity of old paper with foxings. Initially, paper samples are characterized using the conventional absorption and Fourier transform infrared spectroscopies. Optoacoustic method based on laser excitation of short ultrasound transients is used for porosity measurements. The paper porosity is calculated using the theory of two-component mixture with the experimentally determined sound speeds in paper samples saturated with liquids. An increase in the porosity in foxing stains on paper in comparison with the foxing-free fragments is clearly demonstrated.

Fourier Transform Infrared (FT-IR) Microspectroscopy of 20th Century Russian Oil Paintings: Problem of Dating

Analysis of the IR spectra of samples from 230 Russian oil paintings of the 20th century is used to propose a procedure for the threshold estimation of the age of paintings based on measured parameters (intensity ratios of spectral bands). The bands of compounds that are formed upon interaction of pigment (zinc white) with oil are used for dating.

Raman microspectroscopy of old paper samples with foxing.

Diagnostic methods and historical document and artwork (in particular, paper items) analysis using modern physical methods is a topical practical problem. Paper materials exhibit nonuniform degradation with the formation of foxing stains. Correct physico-chemical identification of the structure of foxed fragments depends on the efficiency of the experimental technique and offers guidelines for restoration. Raman spectroscopy makes it possible to characterize old paper samples; however, to our knowledge, a comprehensive Raman analysis of foxing has not been done. In this study, we demonstrate that Raman microspectroscopy allows the identification of spectral changes related to paper aging and foxing formation. The degree of degradation of the rag papers studied here is noticeably less than the degree of degradation of the wood-cellulose papers. The spectral differences among 19th-, 20th-, and 21st-century papers are revealed. The presence of lignin and gypsum filler in the 20th-century paper is demonstrated. Raman data indicate that the foxed fragments exhibit a stronger degradation of the paper. The spectral differences between the foxed and unfoxed fragments are discussed. The results can be used in the restoration of paper documents and artworks, in particular for identification of foxed fragments.

Effect of Laser Radiation on 19th Century Paper

Abstract The effect of laser radiation on a German geographic map printed in 1846 is investigated. The sample is irradiated with pulsed and continuous wave radiation (cw) at a wavelength of 532 nm and fluences of 5 and 3 kJ/cm2, respectively. A visible decrease in discoloration resulting from the pulsed irradiation is demonstrated. ATR FTIR and fluorescence spectroscopy are used for diagnostics. The discolouration of the laser irradiated map after five years and the corresponding spectral changes are discussed. Zusammenfassung Auswirkungen der Laserstrahlung auf Drucke aus dem 19. Jahrhundert Die Auswirkung von Laserstrahlung bei der Reinigung einer 1846 in Deutschland gedruckten Landkarte wird vorgestellt. Die Karte wurde gepulst und kontinuierlich mit einer Wellenlange von 530 nm mit einer Dosis von 5 und kJ/cm² bestrahlt. Dabei konnte die Verfarbung des Objektes reduziert werden. Die Folgen der Strahlungseinwirkung auf das Material wurden mit FTIR im ATR-Modus untersucht. Es wurde beobachtet, dass innerhalb von funf Jahren nach der Laserbestrahlung eine Wiederverfarbung des Objektes eintritt, deren Ursachen diskutiert werden. Résumé Influence de la radiation laser sur du papier datant du 19eme Siecle L’article a pour objectif de presenter l’effet d’une radiation laser sur une carte geograpique allemande imprimee en 1846. L’echantillon a ete irradie par rayonnement pulse et par rayonnement continu de longueur d’onde de 532 nm et une densite de flux de 5 et 3 kJ/cm² respectivement. On a pu demontrer une nette reduction de la decoloration de la carte a l’aide de l’irradiation impulsionnelle. L’echantillon a ete egalement passe au diagnostic de la spectroscopie ATR FTIR et de la spectroscopie fluorescente. On a pu observer que dans un intervalle de cinq annees apres l’irradiation au laser une nouvelle decoloration de l’objet a lieu dont on discutera des causes.

Nano and microcrystallites of KSbOSiO4 in glass matrix as a source of internal strain and fatal corrosion of historic turquoise glass

Investigating long-term fatal corrosion of turquoise lead-potassium historic glass beads, we have detected micro and nano crystallites of orthorhombic KSbOSiO4 (KSS) in glass. We have come to conclusion that KSS precipitates and their clusters give rise to internal glass corrosion. K and Sb being glass dopants form KSS crystallites during glass melt cooling; tensile strain arising in the glass matrix during cooling gives rise to glass cracking and eventually to its rupture and formation of heterogeneous grains. The strain-induced diffusion of impurities, resembling internal gettering in the Si technology, explains changes in glass color. We have also detected Pb2Fe0.5Sb1.5O6.5 nano crystallites in stable yellow lead glass beads. The number density and the sizes of these crystallites are much less than those of the KSS crystallites in turquoise lead-potassium glass, they do not form large clusters; internal cracks also has not been observed in this glass. This may explain the stability of yellow lead glass. The study may be useful for predicting long-term stability of technical glasses as well as for synthesis of nano-KSS/glass composites.

Low-frequency vibrational spectroscopy of proteins with different secondary structures

Abstract. Fourier transform infrared (FTIR) and Raman spectra of proteins with significantly different structures are measured in a spectral interval of 50 to 500  cm−1 and noticeable spectral differences are revealed. Intensities of several spectral bands correlate with contents of secondary structure elements. FTIR spectra of superhelical proteins exhibit developed spectral features that are absent in the spectra of globular proteins. Significant differences of the Raman spectra of proteins that are not directly related to the difference of the secondary structures can be due to differences of tertiary and/or quaternary structure of protein molecules.