Atomic selectivity in dissociative electron attachment to dihalobenzenes

다국어 초록 (Multilingual Abstract)

<P>We investigated electron attachment to three dihalobenzene molecules, bromochlorobenzene (BCB), bromoiodobenzene (BIB) and chloroiodobenzene (CIB), by molecular beam photoelectron spectroscopy. The most prominent product of electron attachment in the anion mass spectra was the atomic fragment of the <I>less</I> electronegative halogen of the two, <I>i.e.</I>, Br<SUP>−</SUP> for BCB and I<SUP>−</SUP> for BIB and CIB. Photoelectron spectroscopy and <I>ab initio</I> calculations suggested that the approaching electron prefers to attack the less electronegative atom, a seemingly counterintuitive finding but consistent with the mass spectrometric result. For the iodine-containing species BIB and CIB, the photoelectron spectrum consists of bands from both the molecular anion and atomic I<SUP>−</SUP>, the latter of which is produced by photodissociation of the former. Molecular orbital analysis revealed that a large degree of orbital energy reordering takes place upon electron attachment. These phenomena were shown to be readily explained by simple molecular orbital theory and the electronegativity of the halogen atoms.</P>

<P>Graphic Abstract</P><P>Atomic selectivity in electron attachment to dihalobenzenes.
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