Mixtures of methylated beta-cyclodextrins were characterized using three different methods of mass spectrometry: ionspray, atmospheric pressure chemical ionization (APCI) and matrix-assisted laser desorption/ionization (MALDI). Each of these methods allows a fast and simple determination of the degree of substitution, and can provide evidence for differences in the methylation of batches which have very similar global degrees of substitution. The three methods are in good qualitative agreement, but there are systematic differences in the quantitative results for the percentages of the various methylated molecules present in a batch. This is attributed to ionization yields which increase with the number of methyl groups, with different slopes for the different methods.
is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. (0 0 4) anatase. An UV to NIR photon conversion is evidenced in the films. Indeed, intense and wellresolved emission lines from Nd 3+ have been observed upon excitation above the TiO 2 bandgap at room temperature. The sensitised emission of Nd 3+ is found to be much efficient in rutile than in anatase structure. Low temperature photoluminescence measurements lead to fine resolved peaks corresponding to the Nd 3+ 4f transitions with different spectral characteristic according to the host matrix used. Photoluminescence dependence temperature evidences that the light emission from Nd 3+ in anatase-based films is probably influenced by the presence of self-trapped excitons or by orbital interaction. Mechanisms of sensitisation host to Nd 3+ are proposed for both matrixes. Finally, the Nd dopant concentration and the microstructure of TiO 2 rutile films are found to affect the photoluminescence emission intensity. Rutile film (2 0 0) oriented is the most adapted host matrix to sensitise 1 at.% Nd 3+ ions for an emission around 1064 nm making such Nd-doped layers interesting for photon conversion by down shifting process.
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