Positron scattering from formic acid

Antonio Zecca, Luca Chiari, A. Sarkar, Marco A. P. Lima, Márcio H. F. Bettega, Kate L. Nixon, Michael J. Brunger
2008 Physical Review A. Atomic, Molecular, and Optical Physics  
We report on measurements of total cross sections for positron scattering from the fundamental molecule formic acid ͑HCOOH͒. In this case, the energy range of our experimental work is 0.3-50.2 eV. Our interpretation of these data was somewhat complicated by the fact that at room temperature, formic acid vapor consists of about 95% monomer and 5% dimer forms, so that the present cross sections represent an average for that ensemble. To assist us in interpreting the data, rigorous Schwinger
more » ... ous Schwinger multichannel level calculations for positron elastic scattering from the formic acid monomer were also undertaken. These calculations, incorporating an accurate model for the target polarization, are found to be in good qualitative agreement with our measured data, particularly when allowance is made for the target beam mixture ͑monomer versus dimer͒ in the experiment.
doi:10.1103/physreva.78.042707 fatcat:zssjx5xr25ecrlfwblfgnyucbi