Microtopographical studies of prism faces of potassium dihydrogen phosphate crystals

Surface structures on prism faces of potassium dihydrogen phosphate crystals grown from aqueous solutions and also by gel method are described and illustrated. Density of growth centres increases as the supersaturation of the mother liquor is increased. Gel grown crystals predominantly show rectangular growth hillocks on their prism faces. In the needle shaped crystals further nucleation extends predominantly along theC axis than at right angles to it. Influence of misoriented guest microcrystals on the growth of the prism faces is described.     

Tetraethylammonium chloride tetrahydrate,a ‘double channel’ host lattice constructed from (H2O)4Cl− tetrahedra linked between vertices

Crystals of (C₂H₅)₄NCl·4H₂O are orthorhombic, space groupCcca, witha=19.104(3),b=23.084(4),c=13.330(3) , andZ=16. The structure features an anionic host lattice constructed from the linkage of (H₂O)₄Cl^– tetrahedra by hydrogen bonds between vertices, generating two open linear channel systems which accommodate the ordered cations. FinalR _F =0.080 for 1516 observed MoK data measured at 22°C. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82035 (12 pages)Dedicated to Professor G. A. Jeffrey     

Solute-Solvent interactions in water-rich mixtures. II. Ionic conductances in water-dimethylsulfoxide mixtures at 25°C

Conductances of sodium bromide, iodide, and perchlorate, potassium chloride, and tetraphenylboride (BPh ₄ ^– ) as well as triisoamyl-n-butylammonium iodide (i-Am₃BuNI) have been measured in aqueous mixtures containing up to 20 mole percent dimethylsulfoxide (DMSO) at 25°C. Experimental data were analyzed by the 1965 Fuoss-Onsager-Skinner (FOS) equation. Single-ion limiting equivalent conductances were calculated by assuming that ₀ (i–Am ₃ BuN ⁺=₀ (BPh ₄ ^– ). The variations of the limiting ionic Walden products are discussed on the basis of acid-base type interactions for cations, and on the basis of structural effects for anions.     

Tunable far-infrared radiation from optically pumped potassium Rydberg transitions

We report the generation of tunable far-infrared radiation by the optical pumping of potassium metal vapor to the13p Rykberg state. Subsequent cascade by stimulated emission is measured at several wavelengths between 76 and 146 cm^–1 with a conversion quantum efficiency of greater than 10 percent. Emission observed in this region are tuned up to 18 GHz by the application of a pulsed Stark field across a parallel-plate heat pipe. Cascade branching to the 11d to 10f transition at 146 cm^–1 is observed which can be tuned up to 7 cm^–1 in our device. Similar branching following excitation up to the 18 p state is shown to provide almost complete tunability in the far-infrared region.Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.     

Phase transition in potassium lithium sulphate

Phase transition and lattice parameter variation with temperature of potassium lithium sulphate have been studied. Precision lattice parameters have been determined at various temperatures, ranging 30°C to 400°C. The diffraction pattern obtained above 435°C differs from that taken at room temperature suggesting a structural change, contrary to the reports of Fischmeister and others. Presented at the Symposium on Crystallography and Crystal Physics, Osmania University, Hyderabad, December 1977.     

Ion-solvent interactions and ionic association in ethanol solutions

The electrical conductivities of potassium halides in ethanol have been measured at 25°C. The limiting molar conductances, ionic association constants and the closest approach parameter were calculated (Justice method) and compared with existing literature data. An inversion of the anion size dependence of ionic association constants for these solutions was observed. The results are explained by what has been called localized solvolysis, in which both the cation and the anion of the solvent separated ion pair are connected with different parts of the separating solvent molecule by donor-acceptor bonding. A correlation between K _A and protonic affinity of anions was found. Similar literature data for aqueous and non-aqueous solutions are also examined.     

Dynamics of H2O molecules in ferroelectric K4Fe(CN)6 · 3H2O

The infrared spectrum of potassium ferrocyanide trihydrate has been recorded both in the para and ferroelectric phases. From a combined study of the IR and Raman spectra, it is concluded that there are two sets of water molecules present in the lattice, one set being involved in stronger hydrogen bonding than the other. The ferroelectric transition appears to be associated with an ordering of the water dipoles.     

以溴化钾-溴酸钾-2′,7′-二氯荧光素为试剂对痕量水杨酸的间接荧光测定法

在pH为3．8－7．90范围内,利用Br2(0.5mol/L H2SO4介质中,Br^-与BrO3^-反应生成）与2′,7′－二氯荧光素反应,使2′,7′－二氯荧光素荧光猝灭,当加入水杨酸时,水杨酸的溴代反应使体系荧光增强,建立了荧光法间接测定痕量水杨酸的新方法。该体系激发波长,发射波长分别为λex505nm,λem520nm,水杨酸浓度在2．0－48．0ug/L范围内呈线性关系,检出限为2．0ug/L。本法选择性好,用于脚癣药水中水杨酸的测定,结果满意。     

流动注射催化光度法测定痕量亚硝酸根

采用流动注射技术与催化光度法相结合,研究了亚硝酸根催化溴酸钾氧化维多利亚绿G的高灵敏度褪色反应,用自制的微机化流动注射分析仪能准确控制时间,优化了实验条件,建立了测定痕量亚硝酸根的流动注射催化光度方法。分析速度每小时80次,克服了催化反应时间难以控制引起的方法精密度,准确不谪的弱点。亚硝酸根在0.0-0.3mg/L范围内,回归方程斜率为0.708;亚硝酸根在0.3-2.0mg/L范围内,回归方程斜率为0.339,方法用于直接测定水中的亚硝酸根获得满意结果。