Effect of Incremental Hydration on Reverse Internal Conversion Vibrational Autodetachment of an Anion

The recently discovered mechanism of reverse internal conversion vibrational autodetachment (RICVAD), by which an excess electron is emitted at specific energies from an isolated hot ground state anion, is mediated by the statistical population of a dipole-bound state. Here, we consider how this process is influenced by the presence of up to two water molecules. Using anion photoelectron imaging of the nitrobenzene radical anion, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>NB</a:mi></a:mrow><a:mo>−</a:mo></a:msup></a:mrow></a:math>, clustered to water molecules, we find that RICVAD remains active for <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msup><c:mrow><c:mi>NB</c:mi></c:mrow><c:mrow><c:mo>−</c:mo></c:mrow></c:msup><c:msub><c:mrow><c:mo stretchy="false">(</c:mo><c:msub><c:mrow><c:mi mathvariant="normal">H</c:mi></c:mrow><c:mrow><c:mn>2</c:mn></c:mrow></c:msub><c:mi mathvariant="normal">O</c:mi><c:mo stretchy="false">)</c:mo></c:mrow><c:mrow><c:mn>1</c:mn></c:mrow></c:msub></c:mrow></c:math>. However, we also find that an additional decay channel opens at higher photoexcitation energies, which arises from dissociation of the cluster upon accessing an electronic resonance of <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:msup><i:mrow><i:mi>NB</i:mi></i:mrow><i:mo>−</i:mo></i:msup><i:msub><i:mrow><i:mo stretchy="false">(</i:mo><i:msub><i:mi mathvariant="normal">H</i:mi><i:mn>2</i:mn></i:msub><i:mi mathvariant="normal">O</i:mi><i:mo stretchy="false">)</i:mo></i:mrow><i:mn>1</i:mn></i:msub></i:mrow></i:math>, forming hot isolated <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mrow><o:msup><o:mrow><o:mi>NB</o:mi></o:mrow><o:mo>−</o:mo></o:msup></o:mrow></o:math>, which then undergoes RICVAD. <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mrow><q:msup><q:mrow><q:mi>NB</q:mi></q:mrow><q:mo>−</q:mo></q:msup><q:msub><q:mrow><q:mo stretchy="false">(</q:mo><q:msub><q:mi mathvariant="normal">H</q:mi><q:mn>2</q:mn></q:msub><q:mi mathvariant="normal">O</q:mi><q:mo stretchy="false">)</q:mo></q:mrow><q:mn>2</q:mn></q:msub></q:mrow></q:math> also shows evidence of RICVAD, but its signatures are obscured by other low energy electron signal. Our work shows that the RICVAD mechanism remains possible in a complex environment and shows how resonance dynamics are influenced by hydration.