Time‐of‐Flight secondary ion mass spectrometry (TOF‐SIMS) using the metal‐cluster‐complex primary ion of Ir 4 (CO) 7 +

An orthogonal acceleration Time‐of‐Flight Secondary Ion Mass Spectrometer (TOF‐SIMS) system has been developed with a metal‐cluster‐complex ion source. The ion source can produce ion beams of massive molecules called metal‐cluster‐complexes such as Ir 4 (CO) 12 , which has a molecular weight higher than 1000 u. Using the system, TOF‐SIMS of a contaminated silicon substrate and a room temperature molten salt (i.e. an ionic liquid) was performed. The ionic liquid N,N‐diethyl‐N‐methyl‐N‐(2‐methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, which has a molecular weight of 426 u, consists of a polyatomic cation, [C 8 H 20 ON] + , and a polyatomic anion, [C 2 F 6 NO 4 S 2 ] − . During SIMS analysis, an analytical sample was bombarded with a continuous primary ion beam of either Ir 4 (CO) 7 + or Ar + in a beam energy of 10 keV at an incident angle of 45°. It was confirmed that the use of Ir 4 (CO) 7 + ions enhanced secondary ion intensity compared with that of Ar + ions. Also, experimental results showed that the bombardment of Ir 4 (CO) 7 + caused less fragmentation. In the case of the ionic liquid, cation‐attached ionic‐liquid molecules were observed in addition to the cation of the ionic liquid. Copyright © 2010 John Wiley & Sons, Ltd.