conjunction with other analytical techniques [5]. Over last two decades, the Raman
spectroscopy became one of the leading techniques in the investigations of the
cultural heritage objects like frescos, mortars, paintings (including wall and rock
paintings), plates, plasters and textiles, pigments, dyes, paints, fibers and inks,
glasses, ivory, resins, porcelain, pottery, bronzes, fossils, seashells, gemstones, and
pearls. The extensive knowledge gathered during the study of such versatile
materials and objects resulted in publishing of several reviews [8–13], databases
[14–20] dealing with the Raman spectroscopy, and its application combined with
other techniques used in this field [5, 21]. Most of the cutting-edge developments
were presented as communications to the International Congress on the
Applications of Raman Spectroscopy in Art and Archaeology (RAA). The most
significant contributions were published in proceedings from consecutive meetings
in London 2001 [22], Ghent 2003 [23], Paris 2005 [24], Modena 2007 [25], Bilbao
2009 [26], Parma 2011 [27], Ljublana 2013 [28], and Wroclaw 2015 [29].
The Raman effect was discovered by Raman in 1928 at the Indian Association
for the Cultivation of Science (IACS) in Calcutta, and just after 2 years, in 1930 his
work was awarded by the Nobel Prize [30]. While Raman spectroscopy has shown
several technical advantages over applications of infrared spectroscopy, it was not
used in the analysis of the art objects until introduction, in 1975, of the Molecular
Optical Laser Examiner (MOLE) Raman microprobe [31]. Over the next 30 years,
several technical developments and innovations introduced into the Raman
instrumentation made this technique an essential tool for examinations of the wide
variety of artistic materials [32]. The Raman spectroscopy is characterized by
several features [9], which made this technique very attractive for the applications
in the analytical archaeometry [33]. The molecular spectra can be collected on very
small particles enabling the work with the microsamples due to its high spatial
resolution (typically ranging between 1 and 10 µm) both in terms of the lateral
resolution and depth profiling (with confocal instruments) [11]. The Raman spectroscopy as a molecular spectroscopic technique allows identification of inorganic
and organic compounds in admixtures without their separation, which is of particular importance in the analysis of paintings. Moreover, the molecular specificity
of the technique is enhanced by the availability of ad hoc-built databases of inorganic and organic materials used in the cultural heritage (CH) field [11]. During
analysis, the laser power is kept at the sufficiently low level preventing the sample
or object from damage. To prevent the most sensitive artifacts from a light-induced
damage coming from the laser, during adjusting and positioning of the laser the
beam is usually de-focused [9]. Thus, the Raman spectroscopy preserves the analyzed specimen intact and enables the use of other, comprehensive elemental and
molecular analysis techniques (FTIR, UV-Vis/FORS, LIBS, XRF, AFM, and
others).
Apart from already mentioned advantages of the Raman spectroscopy, there are
also other specific requirements which have to be fulfilled during the analysis of
cultural heritage objects. It is a quite common situation that sampling is not allowed
and the direct study on the objects is performed in the laboratory or on site (in situ
investigations) with the application of a mobile instrumentation in the place where
16 Spectroscopy in the Analysis of Artworks
485
spectroscopy became one of the leading techniques in the investigations of the
cultural heritage objects like frescos, mortars, paintings (including wall and rock
paintings), plates, plasters and textiles, pigments, dyes, paints, fibers and inks,
glasses, ivory, resins, porcelain, pottery, bronzes, fossils, seashells, gemstones, and
pearls. The extensive knowledge gathered during the study of such versatile
materials and objects resulted in publishing of several reviews [8–13], databases
[14–20] dealing with the Raman spectroscopy, and its application combined with
other techniques used in this field [5, 21]. Most of the cutting-edge developments
were presented as communications to the International Congress on the
Applications of Raman Spectroscopy in Art and Archaeology (RAA). The most
significant contributions were published in proceedings from consecutive meetings
in London 2001 [22], Ghent 2003 [23], Paris 2005 [24], Modena 2007 [25], Bilbao
2009 [26], Parma 2011 [27], Ljublana 2013 [28], and Wroclaw 2015 [29].
The Raman effect was discovered by Raman in 1928 at the Indian Association
for the Cultivation of Science (IACS) in Calcutta, and just after 2 years, in 1930 his
work was awarded by the Nobel Prize [30]. While Raman spectroscopy has shown
several technical advantages over applications of infrared spectroscopy, it was not
used in the analysis of the art objects until introduction, in 1975, of the Molecular
Optical Laser Examiner (MOLE) Raman microprobe [31]. Over the next 30 years,
several technical developments and innovations introduced into the Raman
instrumentation made this technique an essential tool for examinations of the wide
variety of artistic materials [32]. The Raman spectroscopy is characterized by
several features [9], which made this technique very attractive for the applications
in the analytical archaeometry [33]. The molecular spectra can be collected on very
small particles enabling the work with the microsamples due to its high spatial
resolution (typically ranging between 1 and 10 µm) both in terms of the lateral
resolution and depth profiling (with confocal instruments) [11]. The Raman spectroscopy as a molecular spectroscopic technique allows identification of inorganic
and organic compounds in admixtures without their separation, which is of particular importance in the analysis of paintings. Moreover, the molecular specificity
of the technique is enhanced by the availability of ad hoc-built databases of inorganic and organic materials used in the cultural heritage (CH) field [11]. During
analysis, the laser power is kept at the sufficiently low level preventing the sample
or object from damage. To prevent the most sensitive artifacts from a light-induced
damage coming from the laser, during adjusting and positioning of the laser the
beam is usually de-focused [9]. Thus, the Raman spectroscopy preserves the analyzed specimen intact and enables the use of other, comprehensive elemental and
molecular analysis techniques (FTIR, UV-Vis/FORS, LIBS, XRF, AFM, and
others).
Apart from already mentioned advantages of the Raman spectroscopy, there are
also other specific requirements which have to be fulfilled during the analysis of
cultural heritage objects. It is a quite common situation that sampling is not allowed
and the direct study on the objects is performed in the laboratory or on site (in situ
investigations) with the application of a mobile instrumentation in the place where
16 Spectroscopy in the Analysis of Artworks
485