E. Luzzatti

Molecular beam studies of weak interactions for open‐shell systems: The ground and lowest excited states of ArF, KrF, and XeF

Absolute integral cross sections for scattering of ground state fluorine atoms by argon, krypton, and xenon have been measured in the thermal velocity range. Information has been obtained on the long range interaction and using a technique for magnetic analysis of substates of F atoms, a characterization is given for the bonding in the ground and the two lowest excited states of these rare gas fluorides. The potentials are represented as a spherical part and an anisotropic component, which have been obtained in an adiabatic decoupling treatment, including also information from other scattering data. Nonadiabatic coupling matrix elements and other general features of these interactions are also presented.

Scattering of magnetically analyzed F (2P) atoms and their interactions with He, Ne, H2 and CH4

Abstract An improved source of a beam of fluorine atoms has been characterized by magnetic analysis of sublevels for F( 2 P). Ground state and lower lying excited state potential energy curves for the interaction of fluorine atoms with He, Ne, H 2 and CH 4 have been obtained from measurements of integral scattering cross sections at thermal energies. The results for the rare gas systems are discussed in connection with previous work on Ar, Kr, and Xe fluorides; those for the H 2 and CH 4 systems provide information of fine structure effects on the long range pan of entrance channels for reactive potential energy surfaces.

Study of the interactions of atomic and molecular oxygen with O2 and N2 by scattering data

Absolute total scattering cross sections for the O2–O2, O2–N2, O–N2, and O–O2 systems are measured in the thermal energy range. A glory structure is present for O2–O2, O2–N2, and O–N2. For O–N2 this structure appears to be partially quenched due to the anisotropy of the 3P oxygen atom. For O–O2 the structure is almost completely quenched because of the presence of a manifold of interactions. From the analysis of the cross section data, information about the interaction potential of all these systems of atmospheric interest is obtained. For O2–O2 a potential able to reproduce also the spectroscopic and thermophysical data is proposed.

Absolute total elastic cross sections for O2-rare gases scattering

Absolute total elastic cross sections for collisions of O2 with He, Ne, Ar, Kr, Xe have been measured in the velocity range from 0·4 to 2·4 km s-1. Except in the O2-He system, all the cross sections show a glory structure, and the van der Waals constants, C 6, have been obtained from the average ∼ν-2/5 dependence. Total cross sections have been well reproduced by some usual spherically symmetric potential models. Detailed information on the spherical portion of the interaction potential, in the range of the limiting impact parameters, have been extracted.

Scattering of magnetically selected O(3P) atoms: Characterization of the low lying states of the heavy rare gas oxides

Measurements of absolute integral elastic cross sections for scattering of O(3P) atoms, magnetically selected in their sublevels mj=0, are reported at three collision energies in the thermal range for each of the target gases Ar, Kr, and Xe. Anisotropy effects, as measured by differences between cross sections with and without magnetic selection, are negligible for Ar, but of the order of a few percent for Kr and Xe: they show up in the glory structure of cross sections. These data and the dependence on velocity of cross sections without magnetic selection, suggest that in the regions of the very shallow van der Walals wells of KrO and XeO, Π‐type electrostatic interactions are stronger than Σ ones.

The ground and lowest excited states of XeCl by atomic beam scattering

Abstract A Cl( 2 P j ) atom beam is produced in a microwave discharge source and, after velocity selection and magnetic analysis, is used for absolute cross section measurements in collisions with Xe atoms. The data are obtained in the beam velocity range 0.5–2.0 km/s and under three different magnetic sublevel populations of Cl atoms. The analysis of the present data, together with other scattering and spectroscopic properties available for the same system, allows an accurate characterization of the ground and lower lying excited states of XeCl.

Absolute total cross sections for elastic scattering of Ne by Ar, Kr, and Xe: characterization of long range interactions

Absolute total elastic cross sections for Ne-Ar, Ne-Kr, and Ne-Xe collisions have been measured in the 0.5–1.4 km s−1 velocity range. The data have been analyzed on the basis of the Lennard-Jones (12,6) and Buckingham-Corner (6,8,10) potential models. For the long distance ranges mainly probed by the experiments, accurate model independent potential magnitudes have been determined. For Ne-Ar and Ne-Kr systems, semi-empirical calculations previously performed for the long range expansion terms yield potential values which overlap the present determination within the uncertainty limits. For Ne-Xe, a remarkable disagreement between experiment and calculations has been found. Multiparameter potentials previously obtained from differential scattering cross sections appear fairly to reproduce the glory amplitudes and locations.

A study of the XeF molecule by atomic beam scattering with magnetic analysis

Abstract Absolute total cross sections for scattering of fluorine atoms by xenon have been measured in the 0.9–2.0 km s − velocity range. Information is obtained on the long-range interaction and, using a technique for magnetic analysis of substates of F atoms, a characterization is given for the bonding in the two lowest excited states of XeF.

The interaction of atomic and molecular nitrogen with argon by scattering measurements

Absolute integral cross sections for collisions of N2 molecules and N atoms with Ar are measured as a function of velocity at thermal energies. For the N2–Ar case the glory structure observed in the cross section vs velocity plot does not appear to be affected by the anisotropy of the interaction. An analysis in terms of a spherically averaged potential model can be performed thus obtaining a reliable potential function. The N–Ar cross sections presented here are the first collisional study of N atoms leading to significant information on the interaction potential. Although, as shown by the magnetic behavior, the N atom beam is essentially a mixture of atoms in the two metastable 2DJ and 2PJ states, the results obtained, together with other properties of the excited atoms, indicate the presence of a low anisotropy in the N–Ar interaction. An analysis in terms of a simple and yet realistic potential model has been performed obtaining meaningful potential parameters for the N–Ar system. The results for N–Ar...

Scattering experiments on the methane-rare-gas interaction

Abstract Absolute integral cross sections for collisions of CH 4 with Ne, Ar, Kr and Xe are measured as a function of velocity at thermal energies in a molecular beam apparatus. The presence of fully developed glory oscillations indicates that the anisotropy of methane plays only a minor role in these experiments. The data can therefore be treated in terms of a central force-field assumption. The validity of this assumption is confirmed by comparison with the behaviour of other systems through a correlation between the potential parameters and the polarizabilities.