Gallium oxide nanowires were synthesized via chemical vapor deposition of gallium/gallium oxide mixture
and oxygen. The diameter of the nanowires is 30−80 nm with an average value of 50 nm. They consist of
single-crystalline monoclinic crystal. While the nanowires grown without catalyst exhibit a significant planar
defect, the nanowires grown with nickel catalytic nanopaticles are almost defect-free. The growth direction
of the nanowires grown without the catalyst is uniformly [010]. In contrast, the nanowires grown with the
catalyst have random growth direction. X-ray diffraction, Raman spectroscopy, and photoluminescence are
well correlated with the structural characteristics of the nanowires. The result provides an evidence for the
catalyst effect in controlling the structure of nanowires.
Botryococcus braunii, B race is a unique green microalga that produces large amounts of liquid hydrocarbons known as botryococcenes that can be used as a fuel for internal combustion engines. The simplest botryococcene (C 30 ) is metabolized by methylation to give intermediates of C 31 , C 32 , C 33 , and C 34 , with C 34 being the predominant botryococcene in some strains. In the present work we have used Raman spectroscopy to characterize the structure of botryococcenes in an attempt to identify and localize botryococcenes within B. braunii cells. The spectral region from 1600 -1700 cm ؊1 showed (C؍C) stretching bands specific for botryococcenes. Distinct botryococcene Raman bands at 1640 and 1647 cm ؊1 were assigned to the stretching of the C؍C bond in the botryococcene branch and the exomethylene C؍C bonds produced by the methylations, respectively. A Raman band at 1670 cm ؊1 was assigned to the backbone C؍C bond stretching. Density function theory calculations were used to determine the Raman spectra of all botryococcenes to compare computed theoretical values with those observed. The analysis showed that the (C؍C) stretching bands at 1647 and 1670 cm ؊1 are actually composed of several closely spaced bands arising from the six individual C؍C bonds in the molecule. We also used confocal Raman microspectroscopy to map the presence and location of methylated botryococcenes within a colony of B. braunii cells based on the methylation-specific 1647 cm ؊1 botryococcene Raman shift.
Vertically aligned Fe2O3 nanowire arrays were synthesized by the thermal oxidation of Fe foil. They consist of single-crystalline rhombohedral α-Fe2O3 nanocrystals grown along the [112¯0] direction. Most of the nanowires have a sharp tip (diameter=50nm) and beltlike base. The magnetization measurement reveals a Morin temperature of 125K and unique magnetic anisotropy due to the easy axis of the magnetocrystalline anisotropy perpendicular to the nanowire axis.
High-density gallium (Ga)-doped indium oxide (In2O3) nanowires whose Ga content [Ga∕(In+Ga) atomic ratio] is 0%, 7%, and 45%, were synthesized by thermal evaporation. They have an average diameter of 50nm and consist of nearly single-crystalline cubic In2O3 structure with the [010] growth direction. High-resolution x-ray diffraction analysis reveals that as the Ga content increases the position of In2O3 peaks shifts to the higher angle and a crystalline form (Ga,In)2O3 is produced. We estimated a 0.4% reduction of the lattice constant for 45% Ga-doped nanowires.
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