Monodisperse Au₁₁ Clusters Prepared by Soft Landing of Mass Selected Ions

Abstract

Preparation of clean monodisperse samples of clusters and nanoparticles for characterization using cutting-edge analytical techniques is essential to understanding their size-dependent properties. Herein, we report a general method for the preparation of high surface coverage samples of monodisperse clusters containing an exact number of atoms. Polydisperse solutions of diphosphine-capped gold clusters were produced by reduction synthesis. Electrospray ionization was used to introduce the clusters into the gas phase where they were filtered by mass-to-charge ratio allowing clusters of a selected size to be deposited onto carbon coated copper grids at well controlled kinetic energies. Scanning transmission electron microscopy (STEM) analysis of the soft landed clusters confirms their monodispersity and high coverage on the substrate. The soft landing approach may be extended to other materials compatible with an array of available ionization techniques and, therefore, has widespread utility as a means for controlled preparation of monodisperse samples of nanoparticles and clusters for analysis by transmission electron microscopy (TEM).

Synthesis and Characterization of Gold Clusters Ligated with 1,3‐Bis(dicyclohexylphosphino)propane

“…In agreement with previously reported ESI-MS characterization of gold clusters stabilized by dppp, Au 11 L 5 3 + appears as the dominant ion in the mass spectrum owing to its highly stable eight-electron closed-shell electronic structure. [21] Interestingly, this cluster is not observed when dcpp is used as the ligand (Figure 1a). In contrast, less abundant doubly charged cluster species including Au 6 L 3 2 + and Au 10 L 4 2 + are observed with both ligands, whereas Au 6 L 4 2 + (m/z 1415.70) is present only in solution containing dppp-capped gold clusters.…”

Understanding ligand effects in gold clusters using mass spectrometry

“…The large abundance of (11,5) 3+ is attributed to a spherical eight electron closed shell electronic structure which imparts this cluster with enhanced stability. 54,65,77,78 Notably, (11,5) 3+ is not produced when DCPP is used as the ligand instead of DPPP (Figure 2a). Lower abundance clusters including (6,3) 2+ are present with both DCPP and DPPP while (6,4) 2+ is observed only in solutions prepared with DPPP.…”

High-performance liquid chromatography coupled with mass spectrometry for analysis of ultrasmall palladium nanoparticles

“…Since then, MS has been widely adopted in almost all the structural analysis of metal NPs. So far various MS techniques such as MALDI-TOF MS [28,43,44,55,56], ESI-MS [57,58], LDI-MS [59], ion mobility MS [60,61] and fast atom bombardment MS [62] have been applied to explore the metal core mass of all kinds of metal NPs. Among them, MALDI-TOF MS is the most popular MS technique in determining the number of metal atom of NP fractions.…”