HomeSpectroscopic Characterization Laboratory
The X-Ray Photoelectron Spectrophotometer
A Physical Electronics (PHI 5800) ESCA Sustem. XPS is the most widely used tool for any kind of quantitative and qualitative surface analysis, because of its relative simplicity in use and data interpretation.
The information XPS provides about surface layers or thin film structures is of great value. The system is equipped with a sputter ion gun whcich provides increased sputter etch rates and low voltage sputtering capabilities. It has also a dual beam charge neutralizer which provides "hands off" charge neutralization on electrically insulating samples.
Among the information we have obtained using this instrument is the chemical nature and the surface concentration introduced to SWNT after different purification treatments. The technique also provides valuable information about the morphology and chemical state of the active species present in the catalyst used in the CoMoCat process.
Analysis of the percentage of carbon bonded to oxygen at different annealing temperatures. This result demonstrates the gradual removal of functional groups as the temperature increases.
The Fourier Transform MIR-NIR-Vis Spectrophotometer
A modified Bruker Equinox 55 FTIR spectrophotometer. The system can work in the mid and near IR as well as in the visible range. It is also equipped with a diffuse reflectance cell with an in situ reaction chamber. We can perform analysis in solids under controlled atmospheres up to 750K.
Among the information obtained with this instrument are the degree of interaction of active species on the catalyst and also the nature of the functional groups present in SWNT after different purification treatments.
IR spectra of SWNT from three different sources after acid attack. Bands at 1737 and 1722 cm-1 are due to COOH groups
The UV-Visible Spectrophometer
A double beam Shimadzu 2001 UV-Vis spectrophotometer with an integration sphere for diffuse reflectance analysis. We can obtain information about the coordination environment and domain size of the cobalt and molybdenum species present on our most selective catalyst.
The dispersive Raman spectrophotometer
A LabRam Horiba spectrometer, equipped with a CCD multichannel detector and two laser sources: one He-Ne laser with a 633 nm line and an Argon laser giving several excitation lines among them 514, 488 adn 457 nm. The system is also equipped with a heating stage which allows us analysis under controlled atmospheres from sub-ambient temperature up to 1800K.
Nowadays Raman spectroscopy is widely used to characterize SWNT. Indeed, information about tube diameter can be obtained; besides it is possible to distinguish between metallic and semiconducting tubes because of the different Raman spectra for semiconducting and metallic SWNT.