Scientists explain how ions recombine without expected molecular interactions
Researchers have solved a decades-old puzzle in molecular physics by showing that certain ions can break apart and recombine through an unexpected mechanism that doesn't require the molecular interactions scientists thought were necessary. The findings could improve models used in plasma processing, atmospheric chemistry, and semiconductor manufacturing where these reactions occur.
Originaltitel: Dissociative recombination without curve crossings: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>NeH</mml:mi> </mml:mrow> <mml:mo>+</mml:mo> </mml:msup> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>ArH</mml:mi> </mml:mrow> <mml:mo>+</mml:mo> </mml:msup> </mml:math>
Experiments on dissociative recombination on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msup> <a:mrow> <a:mi>ArH</a:mi> </a:mrow> <a:mo>+</a:mo> </a:msup> </a:math> show a small but nonzero cross section at low collision energies. Therefore, dissociative recombination of <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msup> <b:mrow> <b:mi>ArH</b:mi> </b:mrow> <b:mo>+</b:mo> </b:msup> </b:math> , as well as <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msup> <c:mrow> <c:mi>NeH</c:mi> </c:mrow> <c:mo>+</c:mo> </c:msup> </c:math> , is studied theoretically. Accurate fixed-nuclei electron-scattering calculations are performed to produce <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mi>S</d:mi> </d:mrow> </d:math> -matrices that are used as input into a multichannel quantum defect treatment of the dissociation process. Results are compared to available experimental data.