The portable Raman spectrometer Rigaku Xantus-2, has lasers operating at 785 and 1064 nm. For the 785 nm laser set-up, the detector is a CCD cooled by a Peltier system and the power ranges from 30- 490 mW with a spectral resolution between 7 -10 cm-1. The 1064 nm laser set-up instead uses an InGaAs detector and has power varying from 30- 490 mW with a spectral resolution of 15 -18 cm-1. The spatial resolution is about 4 mm2. The Raman probe is very small and light, it weighs less than 3 kilos. The instrument can be efficiently placed on a table to effectuate analyses and moved vertically using a manual lift to gain roughly 50cm (or other); it be mounted on it's specific tripod permitting an easier accessibility to the object under study to a maximum height of ca.2m (with the instrument for horizonal analyses with milimetric positioning) or 2.5m (with the instrument for vertical analyses e.g ceiling) Wheels can be added to facilitate gross movements of the tripod over an extensive area. Analyses can be acquired on a scaffold where the instrument can safely arrive to few mm from the surface under investigation. Measurements are preferably carried out in absence of artificial illumination.
Raman is used in the cultural heritage field for the vast identification and characterization of inorganic and a limited number of organic materials. It is complementary to FT-IR spectroscopy enabling the identification of IR-transparent metal-oxides compounds. The main drawback of this technique is related to high fluorescence emissions which may compete with the scattering phenomena and cover any useful vibrational signals. However, to overcome this limitation we provide portable Raman instrumentation with multiple laser excitations at 785nm and 1064nm which are interchangeable according to the object under study. The long wavelength lines at 785nm and 1064nm limit the fluorescence favouring the examination of both inorganic (pigments, corrosion products,...) and organic (synthetic dyes and pigments, numerous natural dyes and pigments) materials.