While developing a liquid argon detector for dark matter searches we investigate the influence of air contamination on the VUV scintillation yield in gaseous argon at atmospheric pressure. We determine with a radioactive αsource the photon yield for various partial air pressures and different reflectors and wavelength shifters. We find for the fast scintillation component a time constant τ1 = 11.3 ± 2.8 ns, independent of gas purity. However, the decay time of the slow component depends on gas purity and is a good indicator for the total VUV light yield. This dependence is attributed to impurities destroying the long-lived argon excimer states. The population ratio between the slowly and the fast decaying excimer states is determined for α-particles to be 5.5 ± 0.6 in argon gas at 1100 mbar and room temperature. The measured mean life of the slow component is τ2 = 3.140 ± 0.067 µs at a partial air pressure of 2 × 10 −6 mbar.

The electric deflection of mass spectrometrically detected molecular beams has been used to study the molecular geometry of high temperature species by determining whether they possess permanent dipole moments or not, By this means it has been shown that (1) the lithium halide dimers are planar; ( 2 ) lithium oxide, LinO, is linear;( 3 ) the beryllium and magnesium dihalides are linear: the barium dihalides are bent; (4) the group IIB dihalides are linear; ( 5 ) the dihalides of the transition metals from manganese through copper are linear; ( 6 ) the lead dihalides are bent.Many of the structural results are in disagreement with the prediction of simple theories of molecular geometry.Both PbI and Pb12 were found in lead iodide vapor.

The deflection of mass spectrometrically detected beams of CaF2, MnF2, MnCl2, CoF2, NiF2, CuF2, ZnF2, ZnCl2, and HgCl2 by an inhomogeneous electric field has been examined. As found previously, CaF2 deflects in the manner expected for a polar molecule. The remaining molecules listed were found to be nonpolar. These observations are interpreted to imply that while CaF2 has a nonlinear equilibrium geometry the remaining species are linear. The result for HgCl2 is in agreement with a number of previous electron diffraction and spectroscopic studies.

The infrared spectra of BeF2, BeCl2, and MgCl2 in the vapor phase have been measured. Both the asymmetric stretching mode ν3 and the bending mode ν2 were observed for each of these compounds. The observed frequencies are BeF2BeCl2MgCl2ν315201113597cm−1ν2825482295Two bands of the gaseous dimer Be2Cl4 were also observed. Examination of the bending force constants shows that the bonds in the dihalides are strongly directional. The bond stretching force constants of these dihalides are almost identical in magnitude with those of the corresponding monohalides BeF, BeCl, and MgCl.