A microfluidic chip was designed, prepared and tested for integration with a confocal Raman imaging spectrometer with the specific purpose of enabling studies of individual biological cells.
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
In presented work we report results of simple and viable method for producing Au/CNT composites. Chemical composition and crystallographic structure of the Au/CNT composites was confirmed by X-ray diffraction measurements, while transmission and scanning electron microscopy were used to characterize the morphology of nanocrystals as well as the distribution of nanocrystals in the composite. The obtained particles with relatively small diameter (less than 9 nm) were found to be spatially well dispersed on the carbon nanotubes. The density of attached Au-nanoparticles is not sufficient, and cannot be improved by simple increasing gold loading.
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 μm 2 . 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.
Results and discussion
Raman spectroscopy analysisRaman spectroscopy was used to measure signals of nanometer thin polymer films. The typical PSU Raman spectra of thin films with a thickness in the range from 43 to 3 nm are plotted in Fig. 1. The Raman micro-spectroscopy for measurement of thin polymer films
The nucleation rate is essential
in a number of research fields
in order to control crystal formation. The purpose of this study is
to test and optimize the double pulse procedure as a method to investigate
nucleation of calcium carbonate. The induction time, interpreted as
time of formation of postcritical nuclei, was used to separate a stage
in which nucleation is the main process from a stage in which formed
nuclei mainly grow. The induction time was defined for a model mineralization
solution by recording the pH profile of the supersaturated solution
representing the desaturation curve. In the double pulse procedure
nucleation was quenched during the induction time at several time
points, and existing nuclei could grow until a size detectable by
scanning electron microscopy. It was observed, under applied supersaturation
conditions S = 4, that postcritical nuclei formed
directly when the saturation level of the solution was achieved. It
is proposed here that the growth of crystals occurs due to the agglomeration
of nuclei.
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