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Strained InAsP multiquantum wells (MWQs) were grown on InP(100) substrates by solid source molecular beam epitaxy and were characterized to relate structural and optical quality to growth conditions. The multiquantum wells were grown using either dimer or tetramer arsenic (As2 or As4) over the substrate temperature range of 420–535°C. θ-2θ x-ray diffraction measurements showed only slight differences between arsenic compositions in the quantum wells grown with As2 or As4. 300K and 8K photoluminescence full width at half max (FWHM) decreased at higher growth temperatures regardless of the arsenic species used. The 8K photoluminescence FWHM and the surface roughness measured by atomic force microscopy are found to be less sensitive to substrate growth temperature for the multiquantum wells growth with As2 as opposed to As4.

Measurements of g-factors of excited states in barium and cerium fission fragments have been performed using time-integral perturbed angular correlations between secondary-fragment gamma rays. Larmor precession angles have been obtained for the first I-pi = 2(+) states in Ba-144,Ba-146 and Ce-146,Ce-148 as well as for the 9/2(-) state at 117 keV in Ba-143, the 7/2(-) state at 114 keV in Ba-145 and the first 4(+) state in Ce-150. The deduced g-factor fur the 2(+) state in Ba-146 provides substantiating evidence for a downward trend in 2(+) g-factors with increasing neutron number, in line with Interacting Boson Model predictions for the neutron-rich barium isotopes, assuming the quenching of the Z = 64 shell gap for N>88. The static hyperfine fields for implanted barium and cerium isotopes are found to be opposite in sign. These results constitute the first use of secondary-fragment gamma-ray emission in the determination of g-factors of excited states in fission fragments. (C) 1999 Elsevier Science B.V. All rights reserved.

Precise level lifetimes have been measured for various superdeformed bands in Gd-148,Gd-149 and Dy-152 with the Doppler-shift attenuation method From the derived quadrupole moments, Q(0), we find large differences in deformation between the yrast bands and some excited bands in the gadolinium isotopes. Moreover, two of the excited Gd bands and the Dy-152 yrast band, which have identical moments of inertia, have different elongations, supporting the picture that alignment and deformation effects cancel in identical bands.

Based on data obtained with the Eurogam spectrometer, a systematic investigation of superdeformed bands built on single neutron excitations across the N = 86 shell gap has been carried out for gadolinium, terbium, and dysprosium isotopes with 85 ≤ N ≤ 87. In each nucleus, pairs of bands corresponding to degenerate signature partners have been observed. The effective alignment is constant and close to zero for many of the bands, in agreement with cranked shell model calculations for the [402]5/2 and [514]9/2 orbitals. Several bands exhibit non-zero alignments, indicating in some cases the influence of pairing correlations even at high spin and in other cases the occupancy of the [521]3/2 orbital.

InAsP/InP multiquantum well structures were grown by solid source molecular beam epitaxy using either As2 or As4 over a substrate temperature range of 420–535°C. All quantum wells had similar arsenic compositions with a 2.2% standard deviation regardless of arsenic species or growth temperature. This temperature insensitivity of arsenic incorporation in InAsP is in sharp contrast to InGaAsP in which arsenic composition is very sensitive to both substrate temperature and gallium percentage in the compound. The insensitivity of arsenic incorporation in InAsP to substrate temperature may result from growth in a phosphorus rich condition with indium as the only available cation.

The nucleus 202Bi was populated via the 196Pt(11B,5n)202Bi reaction at a beam energy of 75 MeV. Three regular sequences of magnetic dipole transitions have been found. A comparison is made with the known Delta I=1 rotational bands seen in the neighbouring Pb nuclei. An interpretation in terms of collective oblate configurations involving high-K proton and alignable neutron orbitals is suggested.

The temperature-jump relaxation method has been used to measure rate constants for the formation (kf) and dissociation of ternary complexes between 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine and 5-nitrosalicylate (2–)(nsa2–), respectively, and [Zn(nta)(H2O)]–[nta = nitrilotriacetate(3–)]; also for proton transfer between Hnsa–/nsa2– and various buffers. The effects of pH and buffer on the ternary complexation kinetics have been investigated, and independent equilibrium constants are reported for the formation of several [Zn(nta)B](B = buffer) complexes. Values of kf for bipy and nsa2– are similar to those for the corresponding reactions of cobalt(II).

Carbon-13 n.m.r. spectra are reported as a function of pH for mixtures of 2,2′,2″-triaminotriethylamine (tren) and zinc nitrate and/or chloride, and of zinc and tren with 1,2-diaminoethane (en), 1,3-diaminopropane (pn), glycine (gly), and L-alanine (ala). Carbon-13 chemical shifts are also reported as a function of pH for tren and L-alanine (carboxylate carbon) alone. The pH profiles have been analysed by computer and the chemical shifts of the methyl, methylene, methine and carboxylate (in the L-alanine complexes only) carbon atoms determined for the following species: tren, Htren+, H2tren2+, H3tren3+, [Zn(tren)(OH)]+, [Zn(tren)(OH2)]2+, [Zn(tren)(en)]2+, [Zn(tren)(pn)]2+, [Zn(tren)(glyO)]+, [Zn(tren)(alaO)]+, [Zn(tren)(Hpn)]3+, and [Zn(tren)(ala)]2+[glyO = glycinate(1–), alaO = alaninate(1–)]. Stability constants have also been determined for the ternary complexes. The implications of the results as to the co-ordination geometry of zinc in these complexes and the extent of transmission of inductive effects through the metal are discussed.

The structure of the major zinc-containing species in an aqueous solution of 2.20 mol dm–3 ZnCl2+ 2,2′,2″-triaminotriethylamine (tren)(1 : 1) has been investigated by X-ray diffraction. The data have been analysed in terms of six models containing four-, five- or six-coordinate zinc. The preferred model involves the cation [Zn(tren)Cl]+, in which the disposition around the Zn is approximately trigonal-bipyramidal and similar to that reported in two single-crystal determinations on zinc(tren) complexes. The average Zn–N distance is 2.09(2)A and the Zn—Cl distance 2.37(3)A.

NN′-Bis-salicylidene-2,3-diaminobenzofuran, SABF, has been synthesised and is proposed as a stable and inexpensive spectrofluorimetric reagent for determining magnesium in the range 0·1 to 6 µg (2 × 10–3 to 1 × 10–1 p.p.m.). The method is both rapid and sensitive, and has a detection limit of about 10–3 p.p.m. in 50 per cent. aqueous methanol at an apparent pH of 10·5. The orange fluorescence (545 mµ) of the 1 : 1 complex is excited at 475 mµ and can be measured within 15 to 45 minutes of mixing the solutions. Few other ions yield a fluorescence with the reagent and those that do, or that interfere in other ways, may be tolerated in 100-fold molar proportions by simple addition of masking agents. The fluorescent magnesium-SABF complex can be extracted quantitatively into isobutyl methyl ketone without interference from 2000-fold amounts of calcium, thus providing an extremely useful method for determining magnesium in technical materials, etc. To demonstrate this, nine municipal water samples and fourteen blood plasma samples have been analysed successfully for magnesium by the proposed method in a 50 per cent. aqueous methanol medium.

A study is made of the operating parameters and interferences in the atomic absorption determination of an element which is readily atomized (zinc) and an element which is difficult to atomize (molybdenum) with a filament atom reservoir. This device seems better suited in real situations to the determination of involatile elements such as molybdenum and in this instance especially with a hydrogen/ nitrogen-sheathed gas. There were numerous interferences in the case of zinc, but only tungsten produced a significant effect in the determination of molybdenum.

Summary The use of the absorption tube and crucible method of atomization has been evaluated for the atomic-absorption determination of mercury in small sample volumes. The optimal flame type and absorption tube temperature are considered in relation to the sensitivity obtained and the degree of interference from selected extraneous ions. A double absorption peak was obtained for mercury and the limit of detection with a 5-μl sample volume and a triple-row capillary hydrogen diffusion flame was 0.17 ng of mercury. The interferences observed in this method of atomization are not necessarily the same as those common to conventional nebulizer techniques.

We have previously described qualitative measurements concerning the feasibility of atomic absorption spectrometry of mercury at 184.9nm (1). This communication describes the analytical utility of such measurements together with some atomic emission studies using a conventional monochromator system purged with an inert gas to prevent absorption of radiation by oxygen.

The atomic-fluorescence characteristics of bismuth atoms in cool nitrogen-hydrogen and argon-hydrogen diffusion flames burning in air are described. Excitation is obtained from the non-resonance iodine line at 2061.63 A emitted by a microwave-excited electrodeless discharge tube operating at 2450 Mc/s. Fluorescence of the bismuth resonance line at 2061.70 A is observed and also direct-line fluorescence at 2697 and 3025 A. In addition thirteen other much weaker lines were observed and two unidentified lines at 2880 and 2680 A. The emissions at 2628 and 2938 A appear to arise from “thermally assisted direct line fluorescence”. The most intense line at 3025 A permits linear-dependence analytical atomic-fluorescence measurements to be made in the range 0.1–200 ppm with a detection limit of 0.05 ppm and with no problems of source scatter. No interference was observed from hundred-fold concentrations of fourteen ions. Matrix effects from aluminium and magnesium were overcome by raising the temperature of the cool diffusion flames. A bismuth microwave-excited electrodeless discharge tube was used as a source for atomic-absorption measurement in air-hydrogen and air-propane flames at 2231A with a detection limit of 1 ppm and a linear-dependence analytical range of 10–100 ppm. With the iodine microwave-excited electrodeless discharge tube the detection limit for atomic absorption was 10 ppm at 2062 A.

A sensitive spectrofluorimetric procedure for the determination of copper(II) in the range 0.001–0.006 ppm [1–6 × 10 −7 g) has been developed, utilising the ternary complex system [Cu(phen) 2 Rose Bengal]. The complex is extracted into chloroform, diluted with ammoniacal acetone and its fluorescence measured at 570 mμ with excitation at 560 mμ. The fluorescence is constant for several days. The reaction is rendered selective for copper by a preliminary extraction of bis(2, 9-dimethyl-l, 10-phenanthroline)copper(I) nitrate from an EDTA medium.

A carbon filament atom reservoir and a graphite tube atomizer are compared as methods for the determination of germanium by atomic absorption spectrometry. It is shown that the filament technique is not applicable, probably because of loss of the sample as a volatile oxide species which results in inefficient atomization. The design of a small graphite tube atomizer is described; with this, a limit of detection for germanium of 3·10-10 g was found. For a 20-μl sample, this corresponds to a concentration of 0.015 p.p.m. The interfering effect of 13 anions and cations is studied.

The method of minimisation of free energy is used to calculate the flame gas composition and atomisation efficiency of a variety of flames, viz. oxygen-acetylene, oxygen-cyanogen, nitrous oxide-hydrogen, nitric oxide-acetylene, nitrous oxide-propane and air-propane. The results are compared with those obtained in the nitrous oxide-acetylene flame; atomic carbon appears to play a major role in the atomisation of aluminium and silicon in the oxygen-acetylene flame. For general analytical atomic spectroscopic purposes, however, the nitrous oxide-acetylene flame is most suitable.

A capillary burner supporting a nitrogen/hydrogen diffusion flame has been evaluated as a possible means of detection for several volatile fluorides after their gas-chromatographic separation. The fluorides of As, B, C, Ge, I, Mo, P, Re, S, Sb, Se, Si, Te and W were formed by the reaction of the element with chlorine trifluoride, and the intense molecular emission given by each was recorded. An attempt was made to identify the emitting species.

An account is given of the preparation, separation and detection of volatile fluorides. These fluorides are formed by the reaction of chlorine trifluoride with the elements in a specially designed PTFE reaction vessel enclosed in an HF coil. A comparison is also made of a spectroscopic detector with a katharometer for the detection of the fluorides. The separation of volatile fluorides has been reported to be partially successful on perfluorinated materials such as Kel-F oils or waxes on PTFE supports.1–3 The present communication describes a more detailed investigation of these separations and also compares the performance of a newly developed spectroscopic detector4 with a conventional katharometer detector.

A simple high voltage ac spark produced between tungsten electrodes in both nitrogen and argon atmospheres is investigated as an emissive detector for certain organic molecules. Volatile vapours entering the electrode gap lower the resistance and an increased current flows in the spark. The energy available, particularly using nitrogen as a carrier gas, is sufficient to excite UV/visible spectra for various organic compounds; carbon species may be detected at 389 nm (CN), sulphur compounds at 257 nm (CS), halogenated compounds at various tungsten atomic lines and iodine at 206.2 nm (iodine atomic).

Details are given for the production and operation of microwave-excited electrodeless discharge tubes for use as sources in atomic-fluorescence and atomic-absorption spectroscopy. Special reference is made to the tubes for selenium and tellurium and their spectral characteristics are fully discussed. Optimum conditions are given for producing suitably intense and stable sources.

Indium and palladium are determined polarographically with a dropping mercury electrode in a toluene phase, following extraction as the acetylacetonates from aqueous solutions containing 2–10 ppm of the metals (or 0.1–0.5 ppm with a greater ratio of sample volume to solvent volume). Of 31 elements examined, only Co(III), Cr(III), Cu(II), Fe(III), In, Mo(VI), Pd and Ti(IV) gave extractable complexes with reduction waves in the available potential range. Specificity for palladium is obtained by extraction at pH 0.5, and for indium at pH 9 m the presence of cyanide and ascorbic acid as masking agents.

Extremely sensitive and specific colour reactions in both aqueous and organic solutions are described for the spectrophotometric determination of palladium(II) ions. The methods are based upon ternary complex formation with 1,10-phenanthroline or pyridine, and Rose Bengal Extra. Themolar absorptivities are 5 × 104 (aqueous) and 1.25 × 105 (organic) in the presence of a 1000-fold molar excess of EDTA as mass masking agent. Under these conditions there is negligible interference with the pyridine-Rose Bengal Extra system from the 22 cations (including silver, gold and platinum) and seven anions investigated. Both colour reactions take place within 15 min and the complexes are stable for long periods.

Five new methods are described for the preparation of intense narrow line sources of resonance radiation for the alkali and the alkaline earth elements. Optimum conditions for their preparation and operation are described and their suitability for atomic fluorescence spectrometric purposes has been investigated. The most successful method involves a discharge in flowing atmospheric pressure argon in a quartz tube. A small quantity of the element (or element halide) of interest is suspended in a quartz cup in the discharge stream. The resulting source is applicable to a wide range of relatively involatile elements and, although it is somewhat short lived, it may be recharged readily. Microwave excitation of hollow cathode lamps was not found to be very useful for analytical purposes.

The disadvantages of flames as atomizers are summarized, and a new, simple and efficient means of atomization of samples is proposed. The solution on a platinum loop is vaporized by electrical heating into an argon stream. Limits of detection were 10-14 g for cadmium, 10-8 g for mercury, and 10-7 g for gallium. Linear calibration graphs were obtained over 3 or 4 orders of magnitude. Of the various sheathing gases studied, argon was most efficient. The method is relatively insensitive to matrix effects.

Aluminium ions form a ternary complex with Catechol Violet (CV) and cetyltrimethylammonium bromide (CTAB) in which an Al 3 +:CV:CTAB ratio of 1:2:5 is observed. The sensitivity of the binary complex between aluminium and Catechol Violet ϵ 615nm = 1.50 × 10 3 l. mole −1 . mm −1 is enhanced on ternary complex formation to ϵ 670nm = 5.30 × 10 3 l. mole −1 . mm −1 . The colour is formed instantaneously, stabilizes within 20 min, and may be used for the detection of aluminium in the range O.27–54 pm in the presence of EDTA which prevents the interference of most ions. A benzoate extraction procedure for aluminium is used to prevent interference from hundredfold amounts of Cr(VI), Fe(II), Fe(III), Hg(II), Sb(III), Ti(IV) and acetate, but Be, Cr(III), rare earths, V(V), Zr and tartrate must be absent, as must high concentrations of phosphate and fluoride ions.

An attempt is made to prepare microwave-excited electrodeless discharge lamps exhibiting reproducible spectral characteristics. Some of the more important experimental parameters concerned with the preparation and operation of the sources are investigated with respect to spectral characteristics, resonance-line intensity and application of the lamps for atomic absorption and fluorescence purposes. A reproducible method of preparation is described for zinc and cadmium lamps giving improved spectral stability. Optimal results are obtained when microgram quantities of material are used to prepare the lamps. The use of a related series of three-quarter wave resonant cavities is compared.

Samples containing Ag, Be, Bi, Cd, Cu, Ga, Hg, Mg, Pb, Tl, and Zn are vaporized from a tungsten or platinum loop into an argon stream and excited by radiation from electrodeless discharge tubes to produce atomic fluorescence. The integrated atomic fluorescence signals are independent of loop material and loop temperature, and nearly independent of anion type, sample nature, and argon flow rate. The device may have use for fundamental studies for measurement of quantum yields as well as for applied studies of measuring nanogram to picogram quantities of volatile metals in small amounts of sample (about 2 µl needed for analysis). The loop and sheathing device are described.

The effects of lamp preparation, modulation, stability, air cooling, cavity XXX and deterioration of cavity surfaces are considered on the analytical atomic absorbance and atomic fluorescence measurements of mercury, selenium and thallium, for four different types of three-quarter-wave resonant cavities. The efficiency of each cavity is compared and the advantages and disadvantages of each are evaluated with respect to their use in analytical atomic spectrometry.

Atomic-fluorescence measurements, with microwave-excited electrodeless discharge tubes as sources of excitation, are described for thallium and mercury. The limits of detection by atomic fluorescence are 0.12 ppm for thallium and 0.08 ppm for mercury; the corresponding limits by atomic absorption (using the same instrument and source) are 6 and 10 times as great. The preparation, operation and spectral characteristics of thallium and mercury discharge tubes are described and comparisons are made with a thallium hollow cathode lamp and thallium and mercury spectral discharge lamps.

The flame photometry and atomic fluorescence spectroscopy of silicon in nitrogen and argon separated nitrous oxide-acetylene flames have been investigated. The high-temperature, reducing, fuel-rich, argon-separated flame permits the detection of down to 5 and 0.55 p.p.m. of silicon in aqueous solution by flame photometry and atomic fluorescence, respectively. A silicon microwave-excited electrode-less discharge tube was prepared and used for excitation of the atomic fluorescence. The optimum conditions for the determination of silicon by both techniques have been investigated. The fluorescence technique showed no interference from hundredfold amounts (relative to silicon) of 23 ions, but 5 ions interfered in the determination by flame photometry. The fluorescence technique was also largely free from quenching and scatter effects in the presence of these extraneous ions.

A computer method based on the principle of the minimisation of free energy is used to calculate the concentrations of both flame gas and condensed species in flames in thermal equilibrium. The degrees of atomisation of aluminium and silicon are calculated for various fuel-lean, stoichiometric and fuel-rich nitrous oxide-acetylene and air-acetylene flames over a range of temperatures and are found to be both critically dependent on the carbon : total oxygen ratio. When this ratio exceeds unity, the degrees of atomisation are a maximum. The concentrations of 43 species and their dependence on the concentrations of atomic aluminium and silicon are considered, and a comparison is made with the nitrous oxide-acetylene and air-acetylene premixed flames used in practice.

The preparation of microwave-excited electrodeless discharge tubes as spectral-line sources for the atomic-absorption and atomic-fluorescence spectroscopy of titanium, vanadium and zirconium is described. A long, cylindrical, resonant cavity has been found particularly useful for elements such as these.

A commercial high-frequency plasma generator and torch have been modified for application to the analysis of powdered samples. Many of the operating parameters have been investigated and the optimised system has been tested for the analysis of beryllium and boron in magnesium oxide. Two possible methods of sample introduction have been developed.

The polarograhy of 24 metal oxinate complexes extracted into chloroform, IBMK, and ethyl acetate has been investigated, a methanolic solution of lithium chloride being used as base electrolyte. Only 15 complexes gave rise to reduction waves, and interference-free determinations have been developed for indium and thallium(III) in chloroform, and for bismuth, molybdenum and uranium in IBMK. The use of ethyl acetate offered no special advantages, and was the least selective of the three solvents used.

Selenium and tellurium are determined down to 0.25 and 0.12 p pm respectively by measuring the atomic-fluorescence signals at 2040 A and 2143 A respectively. Other possible wavelengths of measurement are considered in detail and the effects of some extraneous ions are examined. Microwave-excited electrodeless discharge tubes are used as spectral sources and intensity measurements are made with a Unicam SP 900A atomic-absorption/flame-emission spectrophotometer. Atomic-absorption measurements are also made with the same sources and spectrophotometer. The advantages of atomic-fluorescence methods and the use of electrodeless discharge tubes are discussed.

Atomic-fluorescence of antimony may be generated in an air-propane flame by nebulizing aqueous solutions of antimony salts whilst irradiating the flame by means of a microwave-excited electrode-less discharge tube operating at 30 W. The strongest fluorescence is exhibited by the (4)S(11 2 ) --> (4)P(1 3 ) 2311 A resonance line and weaker signals are observed at the 2068 and 2176 A resonance lines and at four intercombination lines, at 2598, 2671, 2770 and 2878 A. A process of thermally assisted direct-line fluorescence is postulated to account for the otherwise inexplicable intensity of the 2598 A line emission. Atomic-fluorescence spectroscopy at 2176 A permits the determination of antimony in the range 0.1-120 ppm with a detection limit of 0.05 ppm. With the same equipment and source, the range of measurement for atomic-absorption was 6-120 ppm and the detection limit was 1 ppm. No interferences were observed from 100-fold molar amounts of Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, NH(4), Pb and Zn or from arsenate, chloride, nitrate, phosphate and sulphate.

An atmospheric pressure microwave-excited emissive argon plasma is evaluated for use as a detector in conventional gas-chromatographic analysis. A range of carbon-, oxygen-, nitrogen- and halogen-containing compounds was investigated in order to optimize the sensitivity, linear working range and plasma operating conditions. For the non-selective determination of carbon-containing compounds, the atomic carbon emission at 247.9 nm was found to be most useful. At this wavelength the sensitivities for all the compounds investigated were directly proportional to the amount of carbon in the compounds. The limit of detection for these compounds at 247.9 nm was 1.94·10 -l0 g of carbon per sec. The atomic lines at 206.2 nm (I) and 470.5 nm (Br) were the best for the selective determination of iodine- and bromine-containing compounds respectively, and a new band emission at 256 nm, characteristic of chlorinecontaining compounds, gave good sensitivity.

A non-flame cell utilising a microwave-induced argon plasma at atmospheric pressure is described for emission spectroscopie purposes. The system operates at a microwave power of ca. 40 W (2450 MHz) and requires the use of only minute liquid samples. Optimal operating parameters are investigated and the method is tested on a range of elements. In addition, the use of a high-speed operational amplifier/integrator is described which is capable of following the weak and transient signals common to non-flame methods of atomisation.

The design and construction of a reactor injection assembly for the formation of volatile metal fluorides is described. The sample, in a chlorine trifluoride atmosphere, is heated with a radio-frequency induction heater and the volatile products passed into a hydrogen diffusion flame emission detector. Although this device is primarily intended for use in gas chromatography, this preliminary evaluation is concerned with its application to atomic spectroscopy.

The use of a heated graphite furnace has been evaluated for the atomic absorption determination of zinc. Interferences were found to occur with most elements when present in large amounts; solvent extraction procedures have been investigated to avoid such effects. Results are reported for the solvent extraction and determination of zinc in the range 0.002–1 p.p.m.

Electronic modulation of a selected range of electrodeless discharge tubes is achieved by superimposing a 50 Hz component on the d.c. potential of the anode of the magnetron valve. The effect of modulation is favourable and the usual methods of tube preparation are satisfactory. The source spectra for lead, mercury, silver, thallium and tin are compared with those for the corresponding hollow-cathode lamps and the analytical atomic absorption working curves obtained with the various sources are compared. The sources for lead and tin give considerably higher sensitivity and a wider working range than the hollow-cathode lamps because of the absence of continuous background or non-absorbing lines near the resonance line. The mercury source behaves similarly, probably because of less self-reversal.

The calculations performed in this study were similar to those discussed previously1 utilising a computer technique based upon the minimisation of free energy. The programme is capable of handling forty species at each of ten temperatures and a variety of flame stoichiometries can be studied in one operation. In general the concentrations are calculated in moles per mole of feed and those of gaseous species in volume per cent. The effects of nebulising water have been fully investigated on the nitrous oxide- and air-acetylene flames and are hence neglected in this study.

A non-selective detector is described which can be used in conjunction with the microwave-excited emissive argon plasma detector. The mode of operation is based on the measurement of reflected power and its use is demonstrated with respect to a range of component vapours and permanent gases. The limit of detection for nearly all the species investigated is in the nanogram range and the detector responded to all compounds examined.

The atomic fluorescence characteristics of tin in Ar/H2, Ar/O2/H2 and air/C2H2 flames have been investigated and optimal conditions have been established for the determination of tin. An electronically modulated electrodeless discharge tube excited at 2450 MHz is used as source. Measurement of the fluorescence emission at 303.4 nm in a nitrogen-separated Ar/O2/H2 flame gives a detection limit of 0.1 p.p.m. under almost entirely interference-free conditions. Good analytical curves are obtained in the range 0.5–250 p.p.m. Sn. Of 34 elements examined at 100-fold concentrations, only Ca, Mg, Mo, Sr and U interfered.

Using conductivity and pressure jump relaxation measurements the complex formation of BeSO4 has been studied in mixtures of water and hexamethylphosphoric triamide (HMPT). The rate of substitution of a solvent molecule in the inner solvation sheath of the beryllium ion by a sulphate ion depends on the composition of the solvate species Be(HMPT)i(H2O)4-i and on the type of solvent molecule being replaced by the sulphate ion. Above a mole fraction xHMPT ≥ 0.2 six relaxation processes have been observed. From the conductivity and the kinetic measurements the existence of a Be(SO4)22− complex was inferred in the mixed solvents. Measurements of the densities, dielectric constants and viscosities of the solvent mixtures are reported.