Identification and space charge studies of offline ion sources in ISOLTRAP

With the offline laser ablation ion source that has recently been introduced to the ISOLTRAP experiment at CERN, carbon clusters can be produced and applied for relative and absolute precision mass measurements. The ablation products of three target materials (CuBe, Al, glassy carbon) placed in a new target holder were identified using time-of flight mass spectrometry. With the carbon source, carbon clusters $\text{C}_3^+$ to $\text{C}_{20}^+$ were observed along with hydrocarbons at most mass numbers between $A=36$ and $A=84$. These hy- drocarbons were determined to be largely produced by fragmentation of heavier clusters in collisions in the main buncher and appear to be abundant for $\text{C}_{2n}\text{H}_2^+$, $\text{C}_{2n}\text{H}_5^+$ and $\text{C}_{2n+1}\text{H}^+$. Furthermore, space charge effects in the MR-ToF MS were investigated for three isobaric pairs by examining peak shifts in the ToF spectra. In all cases, attraction between the isotope bunches was observed for increasing ion loads. The derived maximal ion flux in the MR-ToF MS at which the peaks become indistinguishable falls above the expected trend from simulations and earlier measurements.