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The spatial distribution of the activity in a flame-sealed PTB ampoule containing 226Ra solution, incompletely filling the ampoule, was studied by autoradiography and by taking well-collimated gamma-ray spectra in 23 sections of the ampoule. A complex activity profile was observed and used for the Monte Carlo simulation of the ampoule by the GESPECOR code. The computed values of the efficiency transfer factors are in agreement with the experimental data. As a byproduct, the radon partition ratio in the solution–air phases was obtained.

Direct tunable diode laser absorption spectroscopy (TDLAS) was combined in this study with metrological principles on the determination of uncertainties to measure the line strengths of the P36e and P34e line of 12 C 16 O 2 in the ν 1 +ν 3 band at 2.7 µm. Special emphasis was put on traceability and a concise, well-documented uncertainty assessment. We have quantitatively analyzed the uncertainty contributions of different experimental parameters to the uncertainty of the line strength. Establishment of the wavenumber axis and the gas handling procedure proved to be the two major contributors to the final uncertainty. The obtained line strengths at 296 K are 1.593×10 –20 cm/molecule for the P36e and 1.981×10 –20 cm/molecule for the P34e line, with relative expanded uncertainties of 1.1% and 1.3%, respectively ( k =2, corresponding to a 95% confidence level). The measured line strength values are in agreement with literature data (line strengths listed in the HITRAN and GEISA databases), but show an uncertainty, which is at least a factor of 2 lower.

An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories, six of which sent results for photon emission intensities both in absolute and in relative terms. From these results and including previous published values, a consistent decay scheme was worked out, proving that problems in activity measurements have not been due to decay scheme data.

An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories. In order to identify possible biases, the participants were asked to use all possible activity measurement methods available in their laboratory and then to determine their reference value for comparison. Thus, measurement results from 4pibeta-gamma coincidence/anti-coincidence counting, CIEMAT/NIST liquid-scintillation counting, 4pigamma counting with well-type ionization chambers and well-type crystal detectors were given. The results are compared and show a maximum discrepancy of about 1.6%: possible explanations are proposed.

A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of 152 Eu and 134 Cs, and three source-to-detector distances. They are presented and discussed.

The activity of a solution of 64Cu was measured by 4πβ(PC)-γ coincidence counting and liquid scintillation counting using the CIEMAT/NIST method. In addition, 4π ionization chambers were used to establish and preserve calibration factors for secondary standardizations and for a determination of the half-life, for which a value of 12.704(5) h was measured. The photon emission probabilities were determined using gamma-ray spectrometry, finding values of p(511 keV)=0.3512(22) and p(1346 keV)=0.00474(5). The results were checked for consistency, and an ampoule was submitted to the BIPM to have the activity result entered into the database of the International Reference System (SIR), yielding the first entry for this radionuclide.

Various stable phases in the technologically significant intermetallic Fe–Si system were grown by reactive diffusion and via a modified Bridgman method. The product phases were identified by X-ray fluorescence and Mossbauer spectroscopy. From the analysis of the products, their phase sequence and their thicknesses, the growth rate laws and the average component-diffusion coefficients in FeSi are determined. The latter values are in good agreement with the results obtained from tracer diffusion of 59 Fe in FeSi.

We present the results of experimental and theoretical studies of the speed-dependent spin–orbit state distributions of chlorine photofragments produced in the photodissociation of thiophosgene (CSCl 2 ) at 235 nm. Three-dimensional imaging has been employed for observing chlorine photofragments in their ground (Cl) and excited (Cl * ) spin–orbit states. The kinetic energy distributions for Cl and Cl * fragments reflect excitation of several electronic states of the partner fragment CSCl. The spin–orbit branching ratio of P (Cl * )/[ P (Cl) + P (Cl * )] was found to depend on the kinetic recoil energy increasing from 0.1 for low kinetic energy to 0.8 for high kinetic energy. The theoretical interpretation is based on the computation of the CSCl 2 potential energy surfaces (PES) along the C–Cl bond. Two completely different methods of determination of the PES were applied for small and for large values of the C–Cl bond separation R . In case of small and intermediate R values time-dependent density-functional theory has been used. In case of large R values we used an asymptotic method of computation of the PES, which is a generalisation of the Heitler–London approach for many-electron systems. Basis molecular wavefunctions with definite values of the total spin S and the spatial and spin reflection symmetry σ v with respect to reflection of the total electronic wavefunction in the molecular plane were used. The developed theoretical approach was used for the assignment of the molecular states involved in the photodissociation and for the qualitative explanation of the non-statistical population of the spin–orbit states of the chlorine photofragments as function of the kinetic energy. The spin–orbit branching ratio of P (Cl * )/[ P (Cl) + P (Cl * )] predicted by the theory strongly depends on the quantum state of the CSCl fragment. It is large in case of the CSCl(X) + Cl and CSCl(A) + Cl channels and small in case of the CSCl(B) + Cl channel which explains the experimental results.