Dissociative electron attachment to hexafluoroacetylacetone and its bidentate metal complexes M(hfac)2; M = Cu, Pd.

Beta-diketones are a versatile class of compounds that can complex almost any metal in the periodic table of elements. Their metal complexes are found to be fairly stable and generally have sufficient vapor pressure for deposition techniques requiring volatile metal sources. Motivated by the potential role of low energy electrons in focused electron beam induced deposition, we have carried out a crossed electron∕molecular beam study on the dissociative electron attachment and non-dissociative electron attachment (NDEA) to hexafluoroacetylacetone (HFAc) and its bidentate metal complexes: bis-hexafluoroacetylacetonate copper(II), Cu(hfac)2 and bis-hexafluoroacetylacetonate palladium(II), Pd(hfac)2. The relative ion yield curves for the native precursor to the ligand as well as its stable, 16 valence electron Pd(II) complex and open shell, 17 valence electron Cu(II) complex, are presented and compared. For HFAc, the loss of HF leads to the dominant anion observed, and while NDEA is only weakly pronounced for Pd(hfac)2 and loss of hfac(-) is the main dissociation channel, [Cu(hfac)2](-) formation from Cu(hfac)2 dominates. A comparison of the ion yield curves and the associated resonances gives insight into the role of the ligand in the attachment process and highlights the influence of the central metal atom.

Absolute cross sections for dissociative electron attachment and dissociative ionization of cobalt tricarbonyl nitrosyl in the energy range from 0 eV to 140 eV.

We report absolute dissociative electron attachment (DEA) and dissociative ionization (DI) cross sections for electron scattering from the focused electron beam induced deposition (FEBID) precursor Co(CO)(3)NO in the incident electron energy range from 0 to 140 eV. We find that DEA leads mainly to single carbonyl loss with a maximum cross section of 4.1 × 10(-16) cm(2), while fragmentation through DI results mainly in the formation of the bare metal cation Co(+) with a maximum cross section close to 4.6 × 10(-16) cm(2) at 70 eV. Though DEA proceeds in a narrow incident electron energy range, this energy range is found to overlap significantly with the expected energy distribution of secondary electrons (SEs) produced in FEBID. The DI process, on the other hand, is operative over a much wider energy range, but the overlap with the expected SE energy distribution, though significant, is found to be mainly in the threshold region of the individual DI processes.

Gas phase low energy electron induced decomposition of the focused electron beam induced deposition (FEBID) precursor trimethyl (methylcyclopentadienyl) platinum(IV) (MeCpPtMe3).

Relative cross sections for dissociative electron attachment (DEA) and dissociative ionization (DI) of the FEBID precursor, trimethyl (methylcyclopentadienyl) platinum(iv), MeCpPtMe(3), are presented. The most pronounced DEA process is the loss of one methyl radical, while the loss of two or three methyl groups along with hydrogen is the main pathway in DI. Further fragments are formed in DEA and through DI by more complex rearrangement reactions but complete dissociation to bare Pt(-) in DEA or Pt(+) in DI is minor. The transient negative ion (TNI) formation in DEA is discussed and fragmentation mechanisms are proposed for individual processes. From the thermodynamics of the DEA processes we derive a lower limit for the electron affinity of the MeCpPtMe(2) radical (1.7 eV). Appearance energies (AE) of MeCpPtMe(3)(+) (7.7 eV) and Pt(+) (18.6 eV) formation through electron impact ionisation (EI) and through DI, respectively, are determined. Finally, the current DEA and DI results are compared and brought into context with earlier surface science studies on electron-induced decomposition of adsorbed MeCpPtMe(3) as well as gas phase and surface science studies on the FEBID precursors [Co(CO)(3)NO] and [Pt(PF(3))(4)]. These comparisons strongly indicate that DEA is an important process in the electron-induced decomposition of these molecules in FEBID.

Immobilizing water-soluble dendritic electron donors and electron acceptors-phthalocyanines and perylenediimides-onto single wall carbon nanotubes.

The complementary use of spectroscopy and microscopy sheds light onto mutual interactions between semiconducting single wall carbon nanotubes (SWNT) and either a strong dendritic electron acceptor-perylenediimide-or a strong dendritic electron donor-phthalocyanine. Importantly, the stability of the perylenediimide/SWNT electron donor-acceptor hybrids decreases with increasing dendrimer generation. Two effects are thought to be responsible for this trend. With increasing dendrimer generation we enhance (i) the hydrophilicity and (ii) the bulkiness of the resulting perylenediimides. Both effects are synergetic and, in turn, lower the immobilization strength onto SWNT. Owing to the larger size of the phthalocyanines, phthalocyanine/SWNT electron donor-acceptor hybrids, on the other hand, did not reveal such a marked dependence on the dendrimer generation. Several spectroscopies confirmed that distinct ground- and excited-state interactions prevail and that kinetically and spectroscopically well-characterized radical ion pair states are formed within a few picoseconds.