ISSN:0021-2148    

DOI:10.1002/ijch.196900079

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractInfrared spectra of N2O adsorbed on high‐surface area films of evaporated CsCl, CsBr and CsI have been investigated at different surface coverages. The absorption bands appeared nearly always as sharp and well defined multiplets. The relative intensities of their components depended strongly on surface coverage and often there was a correlation in their behaviour on adsorption and on desorption. The spectra have been interpreted in terms of the existence of different adsorption sites or orientations of the molecule on the surfac

ISSN:0021-2148    

DOI:10.1002/ijch.196900080

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractPulse radiolysis of pure metaphosphate glasses yields a transient spectrum with a maximum at 580 run. This new absorption overlaps that of the permanent coloration at 500nm. The decay of the 580nm species extends over a very large time interval, from ∼10−7sec to ∼10−2sec. The effects of doping the glass with CdSO4and Ce2(SO4)3are reported and analyzed. The results are interpreted in terms of various electron and hole centers. It is suggested that non homogeneous (spur or cage) kinetics is responsible for the 580 n

ISSN:0021-2148    

DOI:10.1002/ijch.196900081

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractMeasurements of emission spectra and decay times of Eu3+, Sm3+Tb3+, Dy3+and Gd3+and their concentration dependence were taken in silicate glasses, in the concentration range 0.05–1.00 weight percent, under monochromatic excitation. The results are compared with those obtained in borate glasses. The lower intensities of the main emission lines for all the five R. E., the longer decay times for Tb3+and Sm3+and the shift to shorter wavelengths for Eu3+and Sm3+are explained in terms of the lower field strength seen by the R. E. in silicate glasses and smaller energy transfer probabilitie

ISSN:0021-2148    

DOI:10.1002/ijch.196900082

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractCrystals of potassium chloride and potassium bromide containing trivalent gadolinium were prepared from the melt and also by heating the powdered anhydrous mixtures at 600°C. Their fluorescence spectra consisted of four sharp lines around 3114.3 Å and 3115.1 Å respectively. A single mode of charge compensation for the substituted Gd3+ion with a D3h or C2vsymmetry is proposed. Lifetimes of the fluorescence of these doped crystals as well as of pure GdCl3and GdBrsare of the order of a few ms

ISSN:0021-2148    

DOI:10.1002/ijch.196900083

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractThe activity of lead ions to form heterogeneous nuclei in supersaturated KCl solutions was shown (in previous publications) to account quantitatively for the effect of these ions on the limit of stability of the supersaturated solutions, the rate of crystallization, and the co‐precipitation of the lead ions with the crystallizing salt. Hence the process of crystal growth is described as the deposition of subcolloidal sized nuclei on the crystal seed. Many otherwise perplexing phenomena recorded in the literature, and observed in studies of various aspects related to the crystallization of KCl and NaCl, prove to be a direct consequence of this mechanism of crystallization. Other examples indicate that heteronucleation and a similar growth mechanism may be prevalent in the crystallization of several salts from their aqueous solutions. Some implications and possible applications of the proposed growth mechanism are also discusse

ISSN:0021-2148    

DOI:10.1002/ijch.196900084

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractPotassium chloride and sodium chloride were recrystallized in fractions. Crystallization was effected either by cooling a saturated solution or by isothermal evaporation at reduced pressure. In both cases the active cations (Pb2+or Cd2+) in the co‐precipitate can be replaced by non‐active cations or anions in consequent fractions of the salt crystallized. The phenomenon is attributed to heterogeneous nucleation; the active cations readily form impurity centred nuclei as soon as supersaturation is produced in the solution. The non‐active ions are slow to nucleate. Co‐precipitation is the result of crystal growth by impurity centred macro

ISSN:0021-2148    

DOI:10.1002/ijch.196900085

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractHigh calcium sulpho‐aluminate (3CaO. Al2O3. 3CaSO4. 31H2O—C.S.A.) is a deterioration product of Portland cement found in concrete. It is formed by the attack of sulphate solutions on two of the Portland cement components: hydrated calcium Aluminate and lime. These phenomena fostered a study of the synthesis and stability of calcium sulpho‐aluminate. Results of the experiments on stability of calcium sulphoaluminate in different media are discussed. Measures for preventing the formation of C.S.A. in Portland cement are desc

ISSN:0021-2148    

DOI:10.1002/ijch.196900086

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractThe water present in cation and anion exchange resins for a series of counter‐ions was examined spectroscopically using the 1.9 μ water band. The spectrum of the water in the resins dried to constant weight was characteristic for the counter‐ion present. The changes in the wavelength of the maximum absorbance was compared to the behaviour of the spectrum of ions in solution. The spectra of these resins were also related to the hydration numbers of various

ISSN:0021-2148    

DOI:10.1002/ijch.196900087

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of cellulose in vacuo at 250,275 and 300°C was studied. The decomposition products appearing in different fractions were analyzed and the product ratios at different stages of the reaction were determined. A general scheme is proposed for the process

ISSN:0021-2148    

DOI:10.1002/ijch.196900088

出版商:WILEY‐VCH Verlag    

年代:1969

数据来源: WILEY