Universal Equation for Argon Cluster Size-Dependence of Secondary Ion Spectra in SIMS of Organic Materials

Abstract

A study has been made of the fragmentation of three organic molecules, fluorenylmethyloxycarbonyl-l-pentafluorophenylalanine, tris(8-hydroxyquinolinato)aluminum, and Irganox 1010 under bombardment by argon cluster ions with sizes, n, between 500 and 10000 and for 10 and 20 keV energies, E. It is shown that the intensities of the fragments are governed by the same relation as that for the total volume sputtering yield but that, importantly, the parameter A M that governs the transition in behavior between low and high values of E/n is thought to be related to the energy required to remove that particular fragment from the ensemble of molecules. This causes a great reduction in intensity for the more strongly bound fragments as n is increased, such that, at n = 10000, the intensities of the molecular group peaks, which are weakly bound to the substrate, then dominate the spectrum. For studies involving weakly bound molecules, the low E/n values give the most intense molecular group peaks, but high E/n values give a greater number of small, characteristic fragments. For molecules more strongly bound to the bulk or substrate, it is not as likely that the low E/n data will be so helpful.

Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

“…The rate of increase in this range is consistent with the data for metals by Nelson [31], and all data are consistent with the yield being inversely proportional to the temperature-dependent binding energy according to Trouton's rule. This is consistent with the universal sputtering equation [25,44]. The transition temperature is approximately given by 0.8T M , where T M is the melting temperature in Kelvin.…”

“…Figure 6 shows the change in the NPB monomer yield, Y M , for the Bi 3 + analysis ions as a function of the sputtering yield for the argon clusters. Elsewhere [44], we show that the sputtering yields for Bi 3 + and argon clusters are similar at similar energies. We assume that their behaviors with temperature are similar.…”

“…We assume that their behaviors with temperature are similar. We calculate, for each spectrum, the total ion yield volume (TIYV) [44] and then scale the spectrum so that the TIYV is then proportional to the measured sputtering yield at that temperature. This reduces any scatter arising from repeatability in the sample positioning and the Bi beam currents.…”

“…Using carefully constructed model systems, we conduct a study of the effect of the sample temperature in argon cluster sputter depth profiling of molecular samples. The materials studied are N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (molecular weight 588.74, C 44 SIMS sputter depth profiling of the multilayer samples was conducted using an ION-TOF TOF.SIMS IV (ION-TOF GmbH, Muenster, Germany) operated in a 2-beam mode. A 5 keV Ar 2000 + (Δm/m = 0.3) sputtering beam with an average current of 0.60 nA was set to sputter a 500 μm × 500 μm area of the sample.…”

Dust-aggregate impact into granular matter: A systematic study of the influence of projectile velocity and size on crater formation and grain ejection

“…A number of simulation studies and experiments were performed on the impact of atomic clusters on atomic targets -for example, metals, but also organic targets -with the aim of exploring the dependence of the crater sizes and sputter yields on the projectile characteristics (Anders et al 2004;Samela & Nordlund 2008;Anders et al 2009;Anders & Urbassek 2013;Seah 2013;Seah et al 2014). In these studies it was found that -above a threshold regime -the main projectile characteristic affecting crater volume and ejection yield is the total projectile energy.…”