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Nicolet Almega XR

The Almega XR by Thermo Nicolet is a fully software-controlled Raman-spectrometer suitable for the characterization of any film-sample as well as fluids and powders. The dispersive system, that is available at our institute, comes with two possible excitation-laser-wavelengths: 532 nm (frequency-doubled Neodymium doped Yttrium Orthvanadate diode pumped solid state laser (Nd:YVO4 DPSS), nominal power 25 mW) and 780 nm (external stabilized diode-laser, nominal power 40 mW). In case of the 532 nm as well as the 780 nm laser two spectral-resolution-modes are available, 7 cm-1 and 2 cm-1. The 532 nm and 780 nm laser cover a wavenumber-interval of 6616 to -4443 / 4090 to -710 cm-1 and 3998 to -98 / 4001 to -98 cm-1 for the low- / high-resolution-mode, respectively. The system features four different objectives (10x, 50x, 50x long distance und 100x), which result in spot-sizes of the laser beam on the sample surface between 4 and 1 µm, respectively.

In case of film-samples, a complete motorized sample-stage enables the system to take spectra from several sample positions, line-scans as well as maps with a lateral step-size of 0.2 µm in an automated fashion. In the context of transparent samples the additional option of moving the focus-point in and out of the surface-plane allows for depth-profiles. In combination with the mapping tool depth-profiling is able to provide complete 3-dimensional information of the sample of interest.

At our institute the Almega XR is used to characterize all Raman-active film-systems as well as nanostructures. It particular, it is a very powerful tool in analyzing individual carbon-based nanostructures.