Electron-impact total, multiple-differential elastic, and ionization cross sections of ammonia: A joint theoretical and experimental study

Combined experimental and theoretical studies are performed on the elastic scattering and electron-impact ionization of ammonia <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mo>(</a:mo><a:msub><a:mi>NH</a:mi><a:mn>3</a:mn></a:msub><a:mo>)</a:mo></a:math> in the energy range of <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mn>30</b:mn><b:mspace width="0.16em"/><b:mi>eV</b:mi></b:mrow></b:math> to <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:mn>1</d:mn><d:mspace width="0.16em"/><d:mi>keV</d:mi></d:mrow></d:math>. Differential elastic scattering cross sections are measured across an angular range of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msup><f:mn>5</f:mn><f:mo>∘</f:mo></f:msup></f:math> to <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:msup><g:mn>150</g:mn><g:mo>∘</g:mo></g:msup></g:math>, while doubly differential ionization cross sections were measured in the angular range of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:msup><h:mn>30</h:mn><h:mo>∘</h:mo></h:msup></h:math> to <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:msup><i:mn>135</i:mn><i:mo>∘</i:mo></i:msup></i:math>, with secondary electron energies ranging from <j:math xmlns:j="http://www.w3.org/1998/Math/MathML"><j:mrow><j:mn>5</j:mn><j:mspace width="0.16em"/><j:mi>eV</j:mi></j:mrow></j:math> up to about half the primary electron energy. In parallel with the measurements, theoretical calculations of differential elastic scattering and doubly differential ionization cross sections of <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"><l:msub><l:mi>NH</l:mi><l:mn>3</l:mn></l:msub></l:math> are performed using the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"><m:mrow><m:mi>IAM</m:mi><m:mtext>−</m:mtext><m:mi>SCAR</m:mi><m:mo>+</m:mo><m:mi mathvariant="normal">I</m:mi></m:mrow></m:math> approach, the code, and the distorted wave Born approximation. Reasonably good agreement is observed between the present experimental results and theoretical predictions. Total ionization cross sections, derived by integrating the experimental doubly differential ionization cross sections over the emission angle and secondary electron energies, show excellent agreement with theoretical values obtained using the Binary-Encounter-Bethe model with rescaled orbital binding and mean kinetic energies, and are consistent with experimental data measured by another group using a different method. As a final validation, the sum of the total elastic and ionization cross sections is compared with the recommended total electron scattering cross sections, confirming the consistency of the present experimental results.