An air sampling and analytical system for formaldehyde measurements based on a solid sampler is described. The samplers were tested on a standard atmosphere in the range of 0.2 to 0.8 mg/m3 dry air. A single 340 mg sorbant section had without drying sections a capacity of 16 micrograms formaldehyde in dry air and 3 micrograms at 70% RH, 23 degrees C. The precision of fluorimetric analysis was better than 6% for samples of 300, 600 and 1200 ng formaldehyde, and the accuracy was better than 10%. The precision of a colorimetric analysis was 12% for a 300 ng sample and 2% for 600 and 1200 ng samples. The accuracy of this method was better than 7%. Both the fluorimetric and the colorimetric analyses are found to be accurate and sensitive analytical methods for the determination of low formaldehyde concentrations. However, if measurements of more than 15 minutes duration are taken and a dessicant is used, the accuracy still remains to be verified. Positive interference from acrolein (5-7% interference when equimolar amounts are present) was found, but there was no interference from other aldehydes.

The quantitative determination of formaldehyde in air using the fluorimetric acetylacetone method is described. Known concentrations of formaldehyde were generated and collected in water using abosorbers. The sampling rate was 0.5 1/min, and the sampling volumes varied from 2 to 20 1, depending on the concentration level. Under these conditions the entire sampling and the analytical method were evaluated over a range of 0.2–1.7 mg formaldehyde per m3 of air. The precision of the method expressed as a mean value of the relative standard deviation of 7 independent measurements (6 single determinations each) was (3.4 ± 1.6) % (SD). The accuracy was (101 ± 5) % (SD). The detection limit of the method was estimated to be 0.040 mg formaldehyde per m3 of air (5 liter air sample). Key Words: FormaldehydeAcetylacetone methodAbsorber sampling

A mathematical model of the formaldehyde concentrations in rooms containing particle boards with known emission-rates of formaldehyde is presented. The model is tested in three rooms in a new house. Agreement within ± 15 % is found between calculated and measured formaldehyde concentrations in the rooms before painting and without furniture, carpets, etc.

Autoionisation in 20-500 keV Li+-He collisions has been studied experimentally and absolute cross sections sigma (Li) and sigma (He) have been obtained. A double hump structure is observed for sigma (Li) against impact velocity, while sigma (He) declines surprisingly rapidly. For the four prominent Li lines: (1s2s2)2S, 1s(2s2p3P)a2P, 1s(2s2p1P)b2P and (1s2p2)2D, angular distributions have been measured to yield relative substate populations. The a2P state has a remarkable alignment structure peaked at an impact energy 250 keV with Q(ML=0)/Q(ML=1)=7.5, not seen in the b2P state. The mechanism of a2P excitation is not yet clear.

The cross sections for the formation of excited ${\mathrm{Mg}}^{+}$ states in 20-500 keV ${\mathrm{Mg}}^{++}$-Mg collisions have been measured by optical spectrometry in order to test the validity of the model proposed by Horsdal-Pedersen et al. Phys. Rev. Lett. 41, 1541 (1978) to explain a pronounced structure in the experimental cross section for resonant double-charge transfer in ${\mathrm{Mg}}^{++}$-Mg collisions. The present ${\mathrm{Mg}}^{+}3p$-formation cross sections support the basic assumption in the model, that the interaction between two molecular states, separating into the atomic configurations ${\mathrm{Mg}}^{++}\ensuremath{-}\mathrm{M}\mathrm{g}3{s}^{2}$ and ${\mathrm{Mg}}^{+}3p\ensuremath{-}{\mathrm{Mg}}^{+}3s$ at large intermolecular distances, plays a dominant role in the collision. An extended version of the model is needed to account for the observed formation of ${\mathrm{Mg}}^{+}3d$ and ${\mathrm{Mg}}^{+}4s$ states, the population of the ${\mathrm{Mg}}^{+}3p$ state from the projectile and target, separately, and the polarization of the ${\mathrm{Mg}}^{+}(3p\ensuremath{\rightarrow}3s)$ emission.

Energy spectra of 15-35 eV electrons ejected from 15-70 keV Li+-Ne collisions have been measured. The lines are assigned to neon configurations of the type K 2s22p4 nln'l', K 2s2p5 nln'l', K 2s2p6 nl and K 2s2p5 nl. Several lines which have not been observed or identified before are classified. The spectral pattern changes drastically with increasing energy. At low energies lines from levels with two 2p vacancies dominate. At high energies only lines with a 2s vacancy are observed. Analysis of this strong velocity dependence of the n=2 neon subshell correlation shows that the correlation at the 2 sigma -3 sigma pseudocrossing obeys the Barat-Lichten rule at low velocity and confirms the prescription of Eichler et al. at high velocity. A corresponding critical velocity of nu c approximately=0.3-0.4 au is derived.

The authors present an investigation of collisional excitations in systems characterised by the presence of two valence electrons localised outside closed shells in the energy range 1-300 keV. Two types of systems have been studied: (i) systems such as Mg-rare gases with both valence electrons localised on the projectile, and (ii) systems such as Li, K-Na with one valence electron localised on the projectile and one on the target. Experimentally, the total emission cross sections and polarisations have been measured for the Mg I 31S-31P, 33P-43S, s3P-33D, 33P-3p2 3P, Li I 22S-22P, Na I 32S-32P and K I 42S-42P transitions. The content metastable Mg(3s3p3P) atoms in the applied neutral Mg beams has been determined by means of an optical method based on the Wigner spin conservation rule in low-energy atomic collisions. The Mg(3s2)-He collision has been examined theoretically using a Hartree-Fock frozen-core potential to describe the interaction between the Mg valence electrons and the He atom.

The ejected-electron spectra of highly excited autoionising levels of Li, Be, B and C have been studied by using the projectile electron spectroscopy method. Singly and doubly core-excited states are strongly populated in 100 to 500 keV Li+, Be+, B+ and C+ single collisions with He and CH4. High resolution is obtained by selecting a small observation angle (6.4 degrees ) with respect to the beam axis. Numerous states, previously not seen, have been resolved and identified by comparison with existing theoretical data. For a large number of core-excited states, absolute Auger transition and excitation energies are given. In particular, isoelectronic sequences for singly core-excited lithium-like (Z=2-16) and doubly core-excited helium-like (Z=1-14) autoionising states are studied.

K-shell binding energies in free atoms for Be, B, and C have been obtained to within a few tenths of an eV by applying Auger spectroscopy to fast Be, B, and C ion beams being core-excited in single collisions with CH4and He. The present values, which correspond to the lowest possible ionization energy, i.e., for B, BE1 S=E(1s2s22p)3P0-E(1s22s22p)2P0, are considerably higher than previous values derived from measurements where solid or molecular samples have been used, while good agreement is found with recent free-atom theoretical data.

Be Auger spectra are studied by 25-500 keV Be+ ion impact on H2, He, CH4 and Ne. Several single and doubly core-excited states not previously seen are identified by comparison with calculated transition energies. In particular metastable autoionising Be II (1s2s2p)4P0 states are strongly populated.

Highly excited single and double K-vacancy states in boron are studied using the projectile electron-spectroscopy method. The prominent features of the ejected-electron spectrum of boron are identified and compared with theoretical estimates.