This study deals with assessing the homogeneity of a mixture of ultrasmall nanoparticles differing only by their respective functionalization. While measuring the relative abundance of nanoparticles with specific functionalization is feasible with mass spectrometry, the determination of mixed or segregated moieties is beyond current capabilities. Our approach is based on SIMS with massive projectiles, specifically Au400+4. A distinct feature of bombardment with Au400+4 is abundant emission of multiple secondary ions from one projectile impact. Their analysis allows for examination of coemitted and thus colocalized molecules within the emission area of a single impact (∼10–15 nm in diameter). It is possible to collect the mass spectrum from each projectile impact, which probes individual nanodomains, allowing for examination of molecular homogeneity at the nanoscale.

•PMMA and Irganox 1010 were used to evaluate MetA-SIMS with massive gold projectiles.•Surface metallization reduces the secondary ion yield from Au4004+ impacts.•Secondary ion yields are two orders higher with Au4004+ than with Bi+.•Mass spectra reveal PMMA fragmentation and Irganox 1010 adduct formation.The feasibility of metal-assisted secondary ion mass spectrometry (MetA-SIMS) for increasing secondary ion yields from massive gold projectile impacts is investigated using polymeric and plastic additive test molecules. Poly(methyl methacrylate) (PMMA) and Irganox 1010 surfaces were deposited with various amounts of gold and silver and then analyzed using both Bi+ and Au4004+. The Bi+ primary ion displays a fivefold ion yield increase for some species while the massive gold cluster exhibits significant suppression due to the metal overlayer, with more than a tenfold decrease in ion yields for most species. Consequently, MetA-SIMS does not lead to enhanced secondary ion yields when using the Au4004+ projectile. Overall, the Au4004+ projectile leads to secondary ion yields that are ~2 orders of magnitude larger than for Bi+, even when MetA-SIMS is employed.

This study reports on the secondary ion (SI) emission from individual Au nanoparticles (AuNPs) with secondary ion mass spectrometry (SIMS) operating in event-by-event bombardment/detection mode. This methodology allows one to obtain quantitatively the effective yields of SI emission from individual nano-objects. The analyses of gold cluster emission from a series of AuNPs of different sizes (2, 5, 10, 15, 20, 50 nm in diameter) were conducted with two massive projectiles, 50 keV C602+ and 520 keV Au4004+. The results indicate that the emission of Au2− and Au3− varies as a function of particle size. Due to different mechanisms of energy transfer and energy densities deposited into the NPs, the optimum sizes for maximum Au2− and Au3− emission are: 20 nm for 520 keV Au4004+ and 10 nm for 50 keV C602+. Moreover, the abundance of Au2− and Au3− is also affected by the nature of the projectile. In the case of Au400 impacts, the enhanced SI emission of larger clusters is observed not only from 15 and 20 nm but also from 10 nm AuNPs. The observation of the size- and projectile-dependent SI emission points out the necessity of accurate data interpretation when dealing with nanoscale objects.Graphical abstractHighlights► 1st experimental data on size-dependent secondary ion yields from Au nanoparticles. ► Enhanced secondary ion emission is observed from nanoparticles compared to bulk. ► SI emission depends on nanoprojectile-particle characteristics.

Carbon cluster emission from thin carbon foils (5–40 nm) impacted by individual Aun+q cluster projectiles (95–125 qkeV, n/q = 3–200) reveals features regarding the energy deposition, projectile range, and projectile fate in the matter as a function of the projectile characteristics. For the first time, the secondary ion emission from thin foils has been monitored simultaneously in both forward and backward emission directions. The projectile range and depth of emission were examined as a function of projectile size, energy, and target thickness. A key finding is that the massive cluster impact develops very differently from that of a small polyatomic projectile. The range of the 125 qkeV Au100q+q (q ≈ 4) projectile is estimated to be 20 nm (well beyond the range of an equal velocity Au+), and projectile disintegration occurs at the exit of even a 5 nm thick foil.

In the present work, the advantages of a new, 100 kV platform equipped with a massive gold cluster source for the analysis of native biological surfaces are shown. Inspection of the molecular ion emission as a function of projectile size demonstrates a secondary ion yield increase of ∼100× for 520 keV Au4004+ as compared to 130 keV Au31+ and 43 keV C60. In particular, yields of tens of percent of molecular ions per projectile impact for the most abundant components can be observed with the 520 keV Au4004+ probe. A comparison between 520 keV Au4004+ time-of-flight-secondary ion mass spectrometry (TOF-SIMS) and matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) data showed a similar pattern and similar relative intensities of lipid components across a rat brain sagittal section. The abundant secondary ion yield of analyte-specific ions makes 520 keV Au4004+ projectiles an attractive probe for submicrometer molecular mapping of native surfaces.

Secondary ion mass spectrometry (SIMS) performed in the event-by-event bombardment detection mode when coupled to an electron emission microscope allows one to investigate individual nano-objects. Two groups of Au and Al oxide nano-objects were compared with their bulk counterparts based on their secondary ion and electron emission from individual C60 impacts at 15 and 30 keV total impact energy. Our results show that electron yields depend on the size and surroundings of the nano-object, and at higher impact energies, these differences in electron emission are more pronounced. A second key observation for systems of similar chemical makeup but different surface topography and size is that the emission of secondary ions and electrons is independent of each other.

This Letter presents the first observation of coincidental emission of photons, electrons, and secondary ions from individual C60 keV impacts. An increase in photon, electron, and secondary ion yields is observed as a function of C60 projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV−Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution.Keywords (keywords): electron emission; photon emission; SIMS; surface characterization;