RAMAN LABORATORY
Figure 1 and 2 show the equipment used for Raman spectroscopy measurements. As light source an Argon laser has been employed (Coherent mod. Innova 90), mainly used for excitation at 514.5, 488, 457.9 nm. Laser beam is focused on the sample by a lens (focus 15 cm). The diffused light in normal direction with respect to the incidence beam is focused by a system of two lenses on the input slit of a Jobin Ivon double monochromator (U1000). The main features of the monochromator are the following ones: focal length 1000 mm, two holographic gratings of 110 mm2 with 1800 grooves/mm, dispersion of 9.2 cm-1 at 514.5 nm, resolution of 0.15 cm-1 at 579.1 of Hg line. The output beam is collected into a Peltier cooled photomultiplier and, finally, into a discriminator-amplifier interfaced with a computer which records the signal and the monochromator position.
The polarisation direction of the laser light can be changed by a polarization rotator (l/2) placed before the focalisation lens L1, laser light is already linearly polarised by the Brewster windows into the resonating cavity.
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| figure 1 | figure 2 |