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Characterization of autocatalytic decomposition reactions is important
for the safe handling and storage of energetic materials. Isothermal differential
scanning calorimetry (DSC) has been widely used to detect autocatalytic decomposition
of energetic materials. However, isothermal DSC tests are time consuming and
the choice of experimental temperature is crucial. This paper shows that an
automatic pressure tracking calorimeter (APTAC) can be a reliable and efficient
screening tool for the identification of autocatalytic decomposition behavior
of energetic materials.
Hydroxylamine nitrate (HAN) is an important
member of the hydroxylamine family. High concentrations of HAN are used as
liquid propellants, and low concentrations of HAN are used primarily in the
nuclear industry for decontamination of equipment. Because of its instability
and autocatalytic decomposition behavior, HAN has been involved in several
incidents. 相似文献
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Nickel HA Yeo TM Dzyubenko AB McCombe BD Petrou A Sivachenko AY Schaff W Umansky V 《Physical review letters》2002,88(5):056801
Internal transitions of quasi-two-dimensional, negatively charged magnetoexcitons ( X-) and their evolution with excess electron density have been studied in GaAs/AlGaAs quantum wells. In the dilute electron limit, due to magnetic translational invariance, the optically detected resonance spectra are dominated by bound-to-continuum bands in contrast to the negatively charged donor system D-, which exhibits strictly bound-to-bound transitions. With increasing excess electron density Landau-level filling factors nu<2 the X--like transitions are blueshifted; they are absent for nu>2. The blueshifted transitions are explained in terms of a new type of collective excitation---magnetoplasmons bound to a mobile valence band hole. 相似文献
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E. Tiras D. Zanato S. Mazzucato N. Balkan W.J. Schaff 《Superlattices and Microstructures》2004,36(4-6):473
Temperature dependent measurements of the in-plane photovoltage (IPV) arising from Fermi level fluctuations constitute a powerful tool for determining surface and bulk states and trap activation energies in nominally undoped semiconductors. In this work we report the first IPV measurements on high quality InN grown using the MBE technique. The temperature dependent IPV results coupled with Hall mobility and carrier density measurements provide ample evidence for the existence of a high density of states within the range 54 to 68 meV below the conduction band. Temperature dependent PL measurements indicate a band gap of 0.77 eV where a very weak temperature dependence is observed between 77 and 300 K. These results are shown to be in accord with the IPV measurements. 相似文献
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C. J. Baddeley A. F. Lee R. M. Lambert T. Gie el O. Schaff V. Fernandez K. -M. Schindler A. Theobald C. J. Hirschmugl R. Lindsay A. M. Bradshaw D. P. Woodruff 《Surface science》1998,400(1-3):166-175
A quantitative structure determination of a newly discovered (2×2) adsorption phase of acetylene chemisorbed on Pd{111} has been performed by scanned-energy mode photoelectron diffraction: this phase corresponds to the threshold coverage for the catalytic conversion of acetylene to benzene. The carbon atoms in the C2H2 molecule are located almost over bridge sites with a C–C bond length of 1.34+0.10 Å, the centre of the molecule being positioned almost over a hollow site. Of the two hollow sites the hcp site (directly above a second layer Pd atom) is favoured, particularly by a subset of the data most sensitive to this aspect of the structure, but the full analysis indicates that the fcc site (above a third layer Pd atom) cannot formally be excluded. The adsorption site adopted by acetylene in the higher coverage
phase on Pd{111} is essentially identical. This is the dominant structure in the coverage regime which is catalytically active for the conversion of acetylene to benzene. The implications of these findings for acetylene coupling reactions over Pd{111} are discussed. 相似文献
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Several magnetic and optical processes contribute to the magneto-optical response of nickel thin films after excitation by a femtosecond laser pulse. We achieved a first complete identification by explicitly measuring the time-resolved Kerr ellipticity and rotation, as well as its temperature and magnetic field dependence in epitaxially grown (111) and (001) oriented Cu/Ni/Cu wedges. The first hundreds of femtoseconds the response is dominated by state filling effects. The true demagnetization takes approximately 0.5-1 ps. At the longer (sub-ns) time scales the spins are found to precess in their anisotropy field. Simple and transparent models are introduced to substantiate our interpretation. 相似文献
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