Abstract The electronic absorption spectrum of mesitylene vapour has been photographed on a Q-24 Medium Quartz Spectrograph. The molecule belongs to D3h symmetry and the transition is A→1A2 which is forbidden and due to that the (0,0) band does not appear in the spectrum. The position of (0,0) band in this case has been fixed at 36562 cm?1 with the help of 0→1 and 1→0 transitions. There are 66 bands and most of them are assigned in terms of two ground state frequencies of magnitudes 278 and 519 cm?1 and 7 excited state frequencies of magnitudes 267, 436, 554, 968, 1268, 1386 and 1575 cm?1相似文献
The fabrication of low-dimensional ZnO structures has attracted enormous attention as such nanostructures are expected to
pave the way for many interesting applications in optoelectronics, spin electronics gas sensor technology and biomedicine.
Many reported fabrication methods, especially for ZnO nanorods are mostly based on catalyst-assisted growth techniques that
employ metal-organic sources and other contaminating agents like graphite to grow ZnO nanorods at relatively high temperatures.
We report on catalyst-free vapour-phase epitaxy growth of ZnO nanorods on 6H-SiC and (11-20)Al2O3 using purely elemental sources at relatively low temperatures and growth pressure. ZnO nanorods with widths of 80–900 nm
and lengths of up to 12 μm were obtained. Nanorod density on the order of 109 cm-2 with homogenous luminescence and high purity was also noted.
PACS 81.10.Bk; 81.15.Kk; 81.16.Hc; 78.55.Et; 81.05.Dz; 81.07.Bc 相似文献
Abstract The infrared spectrum of acetonitrile vapour has been obtained in the range below 100 cm?1. There is an absorption band located at 78 cm?1 which is assigned to overlapping intermolecular vibrations of dimer molecules in equilibrium with the monomer species. The equilibrium constant calculated from the pressure dependence of the band intensity amounts to 42 ± 26 1·mol?1. 相似文献
Electron spin resonance (ESR) in polycrystalline diamond films grown by dc arc-jet and microwave plasma chemical vapour deposition is studied. The films with nitrogen impurity concentration up to 8 × 10^18 cm^-3 are also characterized by Raman, cathodoluminescence and optical absorption spectra. The ESR signal from P1 centre with g-factor of 2.0024 (nitrogen impurity atom occupying C site in diamond lattice) is found to exhibit an inversion with increasing the microwave power in an H102 resonator. The spin inversion effect could be of interest for further consideration of N-doped diamonds as a medium for masers operated at room temperature. 相似文献
In this paper we present new equations for accurate calculations of the vapour pressure and enthalpy of aqueous lithium bromide solutions which are commonly used in absorption heat pumps and absorption heat transformers. The number of empirical parameters involved in these equations is much smaller than those in earlier equations. Moreover, the present equations for both vapour pressure and enthalpy involve the same constants as both these equations are derived from a single free energy equation using standard thermodynamic concepts. The present methodology can be used with any other electrolyte for which enthalpy-concentration diagrams may not be readily available. 相似文献
Abstract The near ultra-violet absorption spectrum of parafluoro phenetole has been studied in vapour phase. About 135 red degraded Bands have been measured. These have been explained in terms of five ground state (187, 258, 346, 633 and 855 cm1) and seven excited state (151, 306, 527, 816, 966, 1279 and 1328 cm?1) fundamental frequencies. A red shift of 1243 cm?1 of (0,0) hand relative to that of Phenetole is also observed. 相似文献
Centimetre-long ZnO fibres are synthesized by vapour transportation via thermal evaporation of ZnO powders. The growth process is carried out in a graphite crucible, in which ZnO powder is loaded as the source material, and a silicon wafer is positioned on the top of the crucible as the growth substrate. During the growth process, the source temperature is kept at 800℃ and the substrate temperature is kept at 600℃. Typical growth time to obtain centimetre-long ZnO fibres is 5-10 hours. Scanning electron microscopy (SEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) measurement results show that ZnO fibres are single crystalline with high crystalline quality and very low defects concentration. 相似文献
We have developed a novel advanced VPT set-up. ZnO layers and nanorods were grown employing a specially designed horizontal vapour transport system with elemental sources at relatively low temperatures without catalysis. We employed 6N elemental Zn carried by nitrogen and 99.995% oxygen as reactants. Sapphire, SiC, bulk ZnO and ZnO epitaxial layers were implemented as substrates for ZnO growth. Growth temperatures ranged from 500 to 900 C. Reactor pressures were from 5 mbar to atmospheric pressure. We employed x-ray diffractometry, optical microscopy, scanning electron microscopy and atomic force microscopy to investigate the obtained ZnO samples and the influence of different growth parameters on the ZnO homo- and heteroepitaxial growth and to optimise the set of growth parameters either for both epitaxial layers and nanostructures. We also show that the quality of the VPT grown ZnO epitaxial layers on sapphire can be even higher (evaluated from FWHM of the XRD rocking curves) than the MBE grown ones used as epiwafers for VPT growth. High quality ZnO layers with extremely narrow FWHM of the (0002) rocking curve of 38″ are fabricated employing our VPT approach. 相似文献
Abstract The fluorescence of anthracene vapors and its derivatives initiated by triplet-triplet excitation is observed. The quantum yield of inverce intersystem crossing of anthracene molecules is estimated (10?2). The fluorescence initiated by triplet excitation is quenched by foreign pentane gas, thus permitting an estimation of the lifetime of highly excited triplet molecules. 相似文献
The kinetic process of Sr atom metastable-metastable transition lasers in He-St longitudinal pulsed discharge is analysed and a concise self-consistent physical model is developed. The temporal evolutions of discharge parameters, main paxticle densities, the electron temperature, and the lasing pulses are numerically calculated. The results provided by the model agree well with the experiment, and the temporal behaviour of each laser pulse is explained successfully by the simulation results. 相似文献
The functions of thermal conductivity α(T) and electrical conductivity σ(T) for water vapour, within the temperature intervals 7700–8000 K and 2000–3500 K, were calculated. These calculations were performed by using the UHLENBUSCH'S method and the empirical one. Calculations were based on experimentally determined electric field strength as a function of the arc current and radial temperature distribution in the central zone and in the surrounding of the arc burning in water vapour atmosphere. 相似文献
A new tracer is presented to diagnose tropical cyclones (TCs) and their correspondent rainfall. It is defined as water vapour potential vorticity (WPV) by replacing potential temperature with specific humidity in the potential vorticity (PV). The WPV is compared with PV and moist potential vorticity (MPV) in diagnosing three tropical cyclone cases occurred in North-West Pacific during 10 July to 21 July 2005 (Haitang), 30 July to 9 August 2005 (Matsa) and 25 September to 3 October 2005 (Longwang) separately. The results show that in tracing the track of TCs, WPV is not nicer than PV but better than MPV. While diagnosing TCs' onshore rainfall, WPV is better than MPV in all the three cases. Moreover, the advection of WPV is a good indication of TC rainfall after its landing. 相似文献
A novel lO-period SiC/A1N multilayered structure with a SiC cap layer is prepared by low pressure chemical vapour deposition (LPCVD). The structure with total film thickness of about 1.45~m is deposited on a Si (111) substrate and shows good surface morphology with a smaller rms surface roughness of f.3 nm. According to the secondary ion mass spectroscopy results, good interface of the 10 period SiC/A1N structure and periodic changes of depth profiles of C, Si, A1, N components are obtained by controlling the growth procedure. The structure exhibits the peak reflectivity close to 30% near the wavelength of 322 nm. To the best of our knowledge, this is the first report of growth of the SiC/AIN periodic structure using the home-made LPCVD system. 相似文献
Quasi‐aligned molybdenum oxide nanowires are synthesized on silicon substrate by a thermal evaporation method, at a low temperature of 550 °C without using any catalyst. The diameter of these nanowires is about 100 nm, with steps in the top to form a sharp tip. The field emission measurement shows that these nanowires have strong electron field emission abilities, with high field enhancement factor and a relatively low turn‐on field of 2.16 V µm–1, suggesting that these molybdenum oxide nanowire arrays might be promising candidates as field emitters.