Abstract
We report results from total cross section measurements for positron-acetone scattering. The energy range of these experiments was 0.2-23 eV, while the energy resolution of our positron beam was ~260 meV. The present data clearly highlight the important role played by the strong permanent dipole moment and significant dipole polarisability of the acetone molecule on the low-energy scattering dynamics of this system. For positron energies above about 6 eV the present data is found to be in quite good agreement with the only other total cross section results available in the literature from the Yamaguchi group, however, at lower energies the level of agreement is rather poor. To the best of our knowledge, no theoretical calculations are currently available for positron-acetone scattering. PACS Codes: 34.80.Uv
Highlights
In our previous studies on water [1], tetrahydrofuran [2], 3-hydroxy-tetrahydrofuran [3] and di-hydropyran [4], all of which have significant permanent dipole moments (μ) and dipole polarisabilities (a) of important magnitude, we observed that for each species the total cross sections (TCSs) increased significantly in value with decreasing incident positron impact energies
In a joint collaboration with theorists, in that case for formic acid which possesses a strong dipole moment and dipole polarisability, we were able to explicitly demonstrate [5] that the observed low energy behaviour of the TCSs was due to those (μ, a) physico-chemical properties of the target molecule in question
Very recently [6] the San Diego group has demonstrated the important role that the dipole moment plays in enhancing positron binding to molecules, clearly indicating the crucial role that it plays in positron scattering dynamics
Summary
In our previous studies on water [1], tetrahydrofuran [2], 3-hydroxy-tetrahydrofuran [3] and di-hydropyran [4], all of which have significant permanent dipole moments (μ) and dipole polarisabilities (a) of important magnitude, we observed that for each species the total cross sections (TCSs) increased significantly in value with decreasing incident positron impact energies. 1. Introduction In our previous studies on water [1], tetrahydrofuran [2], 3-hydroxy-tetrahydrofuran [3] and di-hydropyran [4], all of which have significant permanent dipole moments (μ) and dipole polarisabilities (a) of important magnitude, we observed that for each species the total cross sections (TCSs) increased significantly in value with decreasing incident positron impact energies. All these properties of the target, given our previous experience [1,2,3,4,5], would suggest that the total cross section for positron-acetone scattering might be expected to increase dramatically as you go to lower incident positron energies.
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