Sergey Mamedov

Macroscopic phase separation of Se-rich ( x< 1/3) ternary Agy(GexSe1−x)1−y glasses

Temperature modulated differential scanning calorimetry measurements on Ag y (Ge x Se 1-x ) 1-y glasses provide evidence for bimodal glass transition temperatures in Se-rich glasses (x < 1/3). At x = 0.20 and 0.25, thermal measurements performed as a function of Ag content in the 0 ≤ y ≤ 0.25 range reveal that the additive (Ag) segregates into an Ag 2 Se-rich glass phase, possessing a characteristic glass transition temperature T a g = 230 °C, while the remaining base glass displays a second glass transition temperature T b g that systematically increases as its Se content is depleted. The present thermal results are in harmony with Raman scattering, neutron diffraction, dielectric spectroscopy and optical microscopy measurements and suggest that Se-rich glasses in the Ag-Ge-Se ternary system intrinsically phase separate on a macroscopic scale.

Improving and Understanding Three Dimensional Spatial Resolution in a Confocal Raman Microscopy and Raman Hyperspectral Imaging I

Confocal Raman microscopy provides a high spatial resolution because it operates in short wavelength region and utilizes confocal optics. However, the spatial resolution of a confocal Raman microscopy is not well understood, and often confused with the smallest measurable sample size. When performing Raman hyperspectral imaging with a confocal Raman microscope, it is also confused with the smallest distance a mapping stage can step. While all these parameters are pertinent to record a good Raman spectrum or a good Raman map, they are not spatial resolution, and thus have different impacts to the data and results. In this and subsequent papers, we will begin with the theoretical definition, examine the instrumental implementations and present the empirical applications of these parameters with examples.