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

Abstract

Relative cross sections for dissociative electron attachment (DEA) and dissociative ionization (DI) of the FEBID precursor, trimethyl (methylcyclopentadienyl) platinum(IV), MeCpPtMe₃, 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 MeCpPtMe₂ radical (1.7 eV). Appearance energies (AE) of MeCpPtMe₃⁺ (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 MeCpPtMe₃ as well as gas phase and surface science studies on the FEBID precursors [Co(CO)₃NO] and [Pt(PF₃)₄]. These comparisons strongly indicate that DEA is an important process in the electron-induced decomposition of these molecules in FEBID.