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We present an integrated confocal Raman microscope in a focused ion beam scanning electron microscope (FIB SEM). The integrated system enables correlative Raman and electron microscopic analysis combined with focused ion beam sample modification on the same sample location. This provides new opportunities, for example the combination of nanometer resolution with Raman advances the analysis of sub-diffraction-sized particles. Further direct Raman analysis of FIB engineered samples enables in situ investigation of sample changes. The Raman microscope is an add-on module to the electron microscope. The optical objective is brought into the sample chamber, and the laser source, and spectrometer are placed in a module attached onto and outside the chamber. We demonstrate the integrated Raman FIB SEM function with several experiments. First, correlative Raman and electron microscopy is used for the investigation of (sub-)micrometer-sized crystals. Different crystals are identified with Raman, and in combination with SEM the spectral information is combined with structurally visible polymorphs and particle sizes. Analysis of sample changes made with the ion beam is performed on (1) structures milled in a silicon substrate and (2) after milling with the FIB on an organic polymer. Experiments demonstrate the new capabilities of an integrated correlative Raman-FIB-SEM. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The sensitivity of far-field Raman micro-spectroscopy was investigated to determine quantitatively the actual thickness of organic thin films. It is shown that the thickness of organic films can be quantitatively determined down to 3 nm with an error margin of 20% and down to 1.5 nm with an error margin of 100%. Raman imaging of thin-film surfaces with a far-field optical microscope establishes the distribution of a polymer with a lateral resolution of ~400 nm and the homogeneity of the film. Raman images are presented for spin-coated thin films of polysulfone (PSU) with average thicknesses between 3 and 50 nm. In films with an average thickness of 43 nm, the variation in thickness was around 5% for PSU. In films with an average thickness of 3 nm for PSU, the detected thickness variation was 100%. Raman imaging was performed in minutes for a surface area of 900 μm2. The results illustrate the ability of far-field Raman microscopy as a sensitive method to quantitatively determine the thickness of thin films down to the nanometer range. [ABSTRACT FROM AUTHOR]

In clinical practice, the diagnosis and classification of acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) start from the manual examination of stained smears of bone marrow (BM) and peripheral blood (PB) by using an optical microscope. This step is subjective and scarcely reproducible. Therefore, the development of subjective and potentially automatable methods for the recognition of typical AML/MDS cells is necessary. Here we have used Raman spectroscopy for distinguishing myeloblasts, promyelocytes, abnormal promyelocytes and erhytroblasts, which have to be counted for a correct diagnosis and morphological classification of AML and MDS. BM samples from patients affected by four different AML subtypes, mostly characterized by the presence of the four subpopulations selected for this study, were analyzed. First, each cell was scanned by acquiring 4096 spectra, thus obtaining Raman images which demonstrate an accurate description of morphological features characteristic of each subpopulation. Raman imaging coupled with hierarchical cluster analysis permitted the automatic discrimination and localization of the nucleus, the cytoplasm, myeloperoxidase containing granules and haemoglobin. Second, the averaged Raman fingerprint of each cell was analysed by multivariate analysis (principal component analysis and linear discriminant analysis) in order to study the typical vibrational features of each subpopulation and also for the automatic recognition of cells. The leave-one-out cross validation of a Raman-based classification model demonstrated the correct classification of myeloblasts, promyelocytes (normal/abnormal) and erhytroblasts with an accuracy of 100%. Normal and abnormal promyelocytes were distinguished with 95% accuracy. The overall classification accuracy considering the four subpopulations was 98%. This proof-of-concept study shows that Raman micro-spectroscopy could be a valid approach for developing label-free, objective and automatic methods for the morphological classification and counting of cells from AML/MDS patients, in substitution of the manual examination of BM and PB stained smears. [ABSTRACT FROM AUTHOR]

We report on the tuning of the Kondo effect in thin Au films containing a monolayer of cobalt(II) terpyridine complexes by altering the ligand structure around the Co2+ ions by depositing a thin Au capping layer on top of the monolayer on Au by magnetron sputtering (more energetic) and e-beam evaporation (softer). We show that the Kondo effect is slightly enhanced with respect to that of the uncapped film when the cap is deposited by evaporation, and significantly enhanced when magnetron sputtering is used. The Kondo temperature (TK) increases from 3 to 4.2/6.2 K for the evaporated/sputtered caps. X-ray absorption spectroscopy and surface-enhanced Raman spectroscopy investigation showed that the organic ligands remain intact upon Au e-beam evaporation; however, sputtering inflicts significant change in the Co2+ electronic environment. The location of the monolayer-on the surface or embedded in the film-has a small effect. However, the damage of Co-N bonds induced by sputtering has a drastic effect on the increase of the impurity-electron interaction. This opens up the way for tuning of the magnetic impurity states, e.g. spin quantum number, binding energy with respect to the host Fermi energy, and overlap via the ligand structure around the ions. [ABSTRACT FROM AUTHOR]