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Confocal Raman Spectroscopy (confocal + raman_spectroscopy)
Selected AbstractsHigh-Performance Single Crystal Organic Field-Effect Transistors Based on Two Dithiophene-Tetrathiafulvalene (DT-TTF) PolymorphsADVANCED MATERIALS, Issue 37 2010Raphael Pfattner Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on two different polymorphs of dithiophene-tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X-ray diffraction, are reported. OFET devices prepared using different configurations show that both polymorphs exhibited excellent device performance, although the ,-phase revealed charge carrier mobility between two and ten times higher in accordance to the closer stacking of the molecules. [source] Surface-enhanced Raman scattering from analytes adsorbed on gold nanoparticles inside polymer beadsJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2004Mina Larsson Abstract Porous polymer beads with a large inner area were used as a stabilizing matrix for SERS-active gold particles. A commercially available ion exchanger (SOURCETM) was used together with HAuCl4. Absorbance measurements and an x-ray diffraction study confirmed that nanocrystalline gold was obtained in the polymer beads. Transmission electron microscope measurements were performed and showed that larger nanoparticles, 20,100 nm, were obtained on the surface, whereas in the interior smaller particles, approximately 2,10 nm, could be found. Three analytes, mercaptoethanesulfonate, mercaptopropionic acid and thiocyanate, were adsorbed on the gold particles inside the polymer beads. From all analytes enhanced Raman spectra could be obtained. The distribution of analytes adsorbed on gold nanoparticles was investigated by confocal Raman spectroscopy. SERS spectra from the analytes could be observed throughout the polymer bead, indicating a fairly uniform distribution of analytes adsorbed on gold nanoparticles. Copyright © 2004 John Wiley & Sons, Ltd. [source] Drug-induced corneal hydration changes monitored in vivo by non-invasive confocal Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2001Roel J. Erckens It is well established that the state of corneal hydration plays a crucial role in maintaining optimal vision. Therefore, any knowledge that can be obtained non-invasively about the status of corneal hydration could be of significant clinical value. A novel confocal Raman spectroscopic technique was used to monitor non-invasively drug-induced hydration changes in the rabbit cornea. The spectroscopic technique enables one to monitor the changes in water content of the cornea while the confocal probing reduces interference of signals from adjacent tissues and allows for measurement of corneal hydration at various depths. The corneal hydration is altered by applying a dehydrating agent (Muro 128®) topically on the cornea. To determine the corneal hydration status, the OH/CH ratio between the Raman intensity of the water OH mode at 3390 cm,1 and the protein CH stretching mode at 2945 cm,1 is calculated. In the middle of the corneal stroma after 10 min, Muro 128® -treated corneas show an average decrease of about 30% in the OH/CH ratio (1.27 ± 0.13) compared with the untreated corneas (1.76 ± 0.09). In this in vivo model it is possible to monitor the hydration status of the living cornea using the Raman spectroscopic technique. Copyright © 2001 John Wiley & Sons, Ltd. [source] Diffusion Kinetics at Liquid-Glassy Polymer InterphasesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 8 2005Luis Arzondo Abstract Summary: We explored the diffusion mechanisms in a series of liquid/glassy polymer interphases. The diffusion experiments were performed in a unique way: the temperature range studied encompassed the glass transition temperature (Tg) of the glassy matrices. We observed that the diffusion behavior of the liquid polymer was remarkably continuous when passing through the matrix Tg, and that the diffusion modes at the liquid/glassy interphases were very similar to those observed in liquid/liquid polymer diffusion. Diffusion profiles of liquid PS in glassy PPO obtained by confocal Raman spectroscopy. The sample was held at 160,°C for the times indicated in the plot. [source] | ||||||||||