# Packaging Metal Atomic Clusters for Universal and Robust Protection through Cluster Beam Process

## TL;DR

Researchers developed a method to protect metal clusters by embedding them in a polymer, preserving their structure and properties even in harsh conditions.

## Contribution

A universal and robust packaging strategy for gas-phase metal clusters using PMMA through controlled beam implantation is introduced.

## Key findings

- Packaged clusters show robust oxidation resistance even after 30 days of air exposure.
- The method successfully protects a wide variety of metal clusters with different elements and sizes.
- Protection is achieved through stable PMMA-metal bonding and direct implantation into PMMA.

## Abstract

Size‐selected gas‐phase aggregated metal clusters have long been considered as embryos of materials. However, a significant proportion of these clusters are susceptive to damage when exiting vacuum. Consequently, effective protection is highly desirable. Here a cluster packaging and protection strategy is presented based on controllable cluster beam implantation into polymethyl methacrylate (PMMA). In this strategy, the size selection of gas‐phase clusters and the synergistic heating of PMMA during implantation are combined, thereby achieving nondestructive packaging of atomically precise cluster under soft‐landing conditions. The packaged clusters exhibit robust and universal protection. Robustness is reflected in the unaltered oxidation resistance of Mo clusters after exposure to air for over 30 days, as well as the effective agglomeration resistance at temperatures up to 100 °C or in liquid. Universality is demonstrated by the successful protection of a wide range of size‐selected clusters, including Mo clusters ranging from Mo2057 to Mo6, and Ta2057, Cu923, W55, (Re–Mo)147 clusters. This protection is attributed to both a stable, albeit weak PMMA‐Mo bonding, forming Mo─O─C─C species that stabilize the clusters, and the direct implantation of gas‐phase cluster into solid‐phase PMMA. This helps pave the way for further investigation and applications of gas‐phase metal clusters.

Gas‐phase‐aggregated metal clusters are packaged and well‐protected in poly(methyl methacrylate) (PMMA) through controlled beam implantation. The packaged precise clusters show robust protection against oxidation and agglomeration. This protection also demonstrates universality, as it successfully protects metal clusters composed of various elements (including Mo, Ta, Cu, W, and Re) and a broad range of atom numbers (2057‐6).