Browsing by Author "Guo, Hua"

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Infrared spectrum of the simplest Criegee intermediate CH2OO at resolution 0.25 cm(-1) and new assignments of bands 2 nu(9) and nu(5)
(2015-06-07)
Huang, Yu-Hsuan
;
Li, Jun
;
Guo, Hua
;
Lee, Yuan-Pern
;
應用化學系
The simplest Criegee intermediate CH2OO is important in atmospheric chemistry. It has been detected in the reaction of CH2I + O-2 with various spectral methods, including infrared spectroscopy; infrared absorption of CH2OO was recorded at resolution 1.0 cm(-1) in our laboratory. We have improved our system and recorded the infrared spectrum of CH2OO at resolution 0.25 cm(-1) with rotational structures partially resolved. Observed vibrational wavenumbers and relative intensities are improved from those of the previous report and agree well with those predicted with quantum-mechanical calculations using the MULTIMODE method on an accurate potential energy surface. Observed rotational structures also agree with the simulated spectra according to theoretical predictions. In addition to derivation of critical vibrational and rotational parameters of the vibrationally excited states to confirm the assignments, the spectrum with improved resolution provides new assignments for bands 2 nu(9) at 1234.2 cm(-1) and nu(5) at 1213.3 cm(-1); some hot bands and combination bands are also tentatively assigned. (C) 2015 AIP Publishing LLC.
Phase transformation and thermoelectric properties of bismuth-telluride nanowires
(2013)
Hsin, Cheng-Lun
;
Wingert, Matthew
;
Huang, Chun-Wei
;
Guo, Hua
;
Shih, Ten-Jen
Thermoelectric materials have attracted much attention due to the current interest in energy conversion and recent advancements in nano-engineering. A simple approach to synthesize BiTe and Bi2Te3 micro/nanowires was developed by combining solution chemistry reactions and catalyst-free vapor-solid growth. A pathway to transform the as-grown BiTe nanostructures into Bi2Te3 can be identified through the Bi-Te phase diagram. Structural characterization of these products was identified using standard microscopy practices. Meanwhile, thermoelectric properties of individual Bi-Te compound micro/nanowires were determined by the suspended microdevice technique. This approach provides an applicable route to synthesize advanced high performance thermoelectric materials in quantities and can be used for a wide range of low-dimensional structures.