Multi-wavelength visible-Raman spectroscopy was used to characterize HFCVD-grown nanocrystalline diamond films. The components forming the Raman spectra were evaluated following common interpretation models. The withdrawn information was correlated to film properties like grain size, morphology, roughness or refractive index derived from AFM, XRD and Ellipsometry. Full Paper: This paper demonstrates that semiconductor Te is an efficient catalyst for SWNTs growth. By using ethanol as carbon source and TeCl 4 as catalyst procursor superlong well-oriented SWNT arrays with high percentage semiconducting can be generated for various SWNT-based nanodevices fabrication and applications.
The freezing of aqueous solutions and reciprocal distribution of ice and a freeze-concentrated solution (FCS) are poorly understood in spite of their importance in fields ranging from biotechnology and life sciences to geophysics and climate change. Using an optical cryo-miscroscope and differential scanning calorimetry, we demonstrate that upon cooling of citric acid and sucrose solutions a fast freezing process results in a continuous ice framework (IF) and two freeze-concentrated solution regions of different concentrations, FCS1 and FCS2. The FCS1 is maximally freeze-concentrated and interweaves with IF. The less concentrated FCS2 envelops the entire IF/FCS1. We find that upon further cooling, the FCS1 transforms to glass, whereas the slow freezing of FCS2 continues until it is terminated by a FCS2-glass transition. We observe the resumed slow freezing of FCS2 upon subsequent warming. The net thermal effect of the resumed freezing and a reverse glass-FCS1 transition produces the Ttr2-transition which before has only been observed upon warming of frozen hydrocarbon solutions and which nature has remained misunderstood for decades.
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