摘要:

AbstractOH*(A2Σ+) and OH(X2Π) concentration‐time‐profiles were measured in the gas phase reaction system C2H2/O/H at 2.66 mbar and 298 K in a discharge flow system for largely varying initial conditions. The well established chemiluminescence reaction CH + O2→ OH*(A2Σ+) + CO connects the experimental OH*(A2Σ+) concentrations to the concentrations of the intermediate CH(X2Π) which is an important precursor of higher hydrocarbons. Computer analysis showed that the reaction CH2+ H → CH + H2is the major CH formation reaction with a rate constantk4of about 5 · 1013cm3mol−1s−1. Reaction CH2+ O → CH + OH does not contribute significantly to either CH or OH formation. A rate constantk28= 4.8 · 1010cm3

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860702

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractA kinetic study of the chemiluminescence of the emitters CH(A2Δ), C2(d3Πg) and C2H*in a mixture of acetylene, oxygen and hydrogen atoms has been performed using a low pressure discharge flow reactor at 2.66 mbar and 298 K under largely varying initial conditions. The absolute concentrations of the emitters could be quantitatively simulated and correlated to the simultaneous formation of higher hydrocarbons in this system when the following formation reactions of the excited species are assumedThese reactions are in particular accord with the dependence of the chemiluminescence on the concentration of free hydrogen atom

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860703

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractEqual concentrations of HO and H were generated by flash photolysing small amounts of H2O diluted in N2at a pressure of about one atmosphere. Using sensitive detection by resonance absorption, the HO radicals were monitored in the presence and in the absence of O2. In the presence of O2, the radicals were found to disappear significantly faster than in the absence of O2. This enhanced decay is attributed to the fast reaction of HO with HO2. Using simple kinetic arguments and computer modeling, the rate constant,k1, for the title reaction is estimated to be 1.1 · 10−10cm3s−1(+25%;

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860704

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractTime and wavelength‐resolved infrared emission techniques are used to study the multiphoton excitation and dissociation of CF3J. Fluorescence is detected from thev1‐(sym. CF3‐stretch),v4‐(asym. CF3‐stretch), andv2‐(sym. CF3‐deform.)‐vibrational modes of CF3J and at laserenergies exceeding the dissociation threshold also from CF3radicals and excited iodine atoms J*(2P1/2→2P3/2). – The pumpedv1‐ladder of states (v1,v≧ 1) is populated collision‐free as the fluorescence rise times show. Strikingly different, thev4(v= 1)‐mode is populated via collisions, while the higherv4‐states are populated collision‐free. Thev4(v= 1)‐population rate is measured to be (7.1 ± 2). 1013cm3mol−1s−1. – Thev1‐ andv4‐emissions show a red‐shift of the band peak and band broadning with increasing laser energy according to higher quanta excitation. – To longer observation times thev1‐ andv4‐bands shift blue again and narrow somewhat according to vibrational relaxation. However at higher laser energies both band peaks do not shift back to their fundamental frequencies, but only decrease in intensity to longer times. This is interpreted as relaxation of these modes by coupling to low frequency modes like the C‐J‐vibrations, which can be easier V‐R, T deactivated. – At laser energies exceeding the dissociation threshold a new emission band is found at 1245 cm−1, due to the C‐F‐stretch of the vibrationally excited CF3‐radical. The rise of the fluorescence signal consists of two parts arising from initially vibrationally hot CF+3and initially cold CF3, which is subsequently excited by collisions with a rate of (1.7 ± 0.5) · 1013cm3mol−1s−1. – Activation‐ and deactivation rates for various spectral fe

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860705

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe hydrogen pressure in equilibrium with liquid phases of the system sodium‐sodium hydride has been measured from 650 to 900 °C and up to 900 bar. A detailed description of the apparatus is given. The autoclave was of a nickel base superalloy and contained an outer and an inner compartment with equilibrated hydrogen pressures. At 900°C and 650 bar the maximum solubility of NaH in liquid Na is 19 mole percent. Sieverts' law is closely obeyed to 5% NaH. Sodium solubility in the liquid NaH is below 2%. The melting point of NaH was found at 632 °C and 106 bar, the enthalpy and entropy of fusion as 26.2 ± 0.7 kJ mol−1and 29.0 ± 0.8 JK−1mol−1. The enthalpy of solution of liquid NaH in liquid Na is 27.4 kJ mol−1. Equations and data for solubility, activity coefficients etc. of NaH are given. The critical solution point for Na and NaH is estimated to be at 1500 ± 70 K, 2500 ± 600 bar andx(Na

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860706

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe Ehrenfest scheme of classification of thermodynamic transitions in one component systems is extended to multicomponent systems. Some possible applications of the derived relations on unsharp transition phenomena of the second order type in mixed phases are discussed.

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860707

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe dynamic viscosities, the activation energies of the viscous flowEηa, and the mass densities ϱ were measured for the binary systems 12‐crown‐4/D2O, 12‐crown‐4/ethylene glycol, 12‐crown‐4/methanol, 15‐crown‐5/D2O, 15‐crown‐5/ethylene glycol, and 15‐crown‐5/methanol as a function of temperatureTand mole fractionx1of the crown ether. – Mixtures with bifunctional “alcohols” (D2O, HOCH2CH2OH) showed “broad maxima” in their isotherms η(x1,T= const) andEηa(x1,T= const), respectively. Correspondingly, the self‐diffusion coefficientsD1of the crown ethers in these mixtures pass a minimum. Quite different is the transport behaviour of the crown ether/methanol system; it behaves with respect to η andD1almost as ideal system. – The results are discussed by assuming association in the systems, and such a model is also valid for dioxan

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860708

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe phase behaviour of mixtures of ethylene and polyethylene was studied under pressures up to 200 MPa at temperatures between 383 and 473 K simultaneously by optical and analytical measurements. Three different low density polyethylenes with number average molecular weights of 1100, 19500 and 55000 g/mol were used. In order to show the influence of long chain branching the results were compared with datas published on mixtures of ethylene and linear polyethylenes. It was found that the heterogeneous region extends with rising molecular weight of the polymer and falling temperatures. With branched polyethylenes the critical pressure was lower. The dependency of the critical pressure on the molecular weight and the branching could be expressed by an equation analogous to the relation between the critical temperature and the polymer molecular weight in diluted solutions.

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860709

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractExcess and interaction second virial coefficients have been measured over the temperature range 290 – 320 K for binary systems of SF6with He, Ne, Ar, Kr, Xe, N2, O2, CO2, CH4, and CF4. The excess virial coefficients are estimated to have an accuracy of 0.2 cm3mol−1and have been used to calculate molar excess enthalpies for each system at 30

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860710

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractDiffusion coefficients and thermal diffusion factors are reported for binary mixtures of deuterium with neon, argon, krypton and xenon at 300 K. The data are used to test the Chapman‐Enskog theory and some of the potential functions which have been reported for these system

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860711

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY