Magic Numbers for Packing Adamantane in Helium Droplets: Cluster Cations, Dications and Trications

TL;DR

This study reports the first observation of large adamantane cluster cations, dications, and trications formed in helium droplets, revealing stable 'magic number' cluster structures with specific packing arrangements, unaffected by charge state.

Contribution

It is the first to identify stable large adamantane cluster ions and their 'magic number' mass peaks, advancing understanding of cluster stability and structure in helium droplets.

Findings

Identification of 'magic number' peaks indicating stable cluster structures

Formation of large cluster ions via helium droplet ionization methods

No significant transformation into adamantoids or microdiamonds observed

Abstract

We report the first observation of cations, dications and trications of large clusters of adamantane. Cluster formation was initiated near 0 K in helium droplets and ionization was achieved with one or more collisions with energetic He species (He$^{\star}$, He$^{+}$ or He$^{\star}$$^{-}$). The occurrence of Coulomb explosion appeared to discriminate against the formation of small multiply charged clusters. High resolution mass spectrometry revealed the presence of "magic number" m/z peaks that can be attributed to the packing of adamantane molecules into cluster structures of special stability involving preferred arrangements of these molecules. These abundance anomalies were seen to be independent of charge state. While some dehydrogenation of adamantane and its clusters was seen as well, no major transformations into adamantoids or microdiamonds were observed.