Chapter 1
An Overview of Metal Clusters and Their
Reactivity
Atomic clusters containing a few to a few thousand atoms are emerging as a frontier
area in science. The properties in this size regime are controlled by the discrete
quantum conditions associated with reduced size as opposed to bulk where the
properties are insensitive to the boundaries. Consequently, the physical, electronic,
magnetic, and chemical properties are all found to change with size and in many
cases, the properties at small sizes are different from those of bulk. Due to quantum
effects, the addition of a single atom or an electron can lead to a completely different
behavior. Consider the case of gold. Bulk gold is a noble element that is resistant
to corrosion. Yet, small gold clusters are found to be excellent catalysts where the
activity is highly dependent on the size. Bulk rhodium is non-magnetic while small
rhodium clusters are found to exhibit large spin magnetic moments. The novel behaviors have led to the expectation that it should be possible to design materials with
controlled properties by assembling size-selected clusters as the building blocks.
While the field of clusters can be traced to the formation of C 60 clusters as existed in
intersteller matter, the recent interest is inspired by the development in experimental
techniques over the past four decades that have enabled synthesis and characterization
of atomic clusters of finite size and any composition. In this book, we will primarily
focus on clusters of metallic elements. These clusters bridge several interdisciplines
by combining ideas within atomic, molecular and condensed matter with nuclear
physics, chemistry, and biology [1–6]. Several amongest research topics in metal
clusters, including structure and stability, size-dependent evolution and electronic
behavior, thermal property, catalysis and reactivity etc., have been widely investigated
[7–14]. In particular, techniques such as flow tube reactors coupled with quadrupole
mass spectrometers, and a combination of quadrupole and octupole fields in a guided
ion beam arrangement have been used in studies of cluster reactions, which are retrospect to about 40 years ago [15–25]. In recent years, extensive research interest has
been stimulated by ligand-protected metal clusters [26–33], showing novel structural
diversity and potential applications in catalysis, photochemistry, chemo-sensing, and
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Singapore Pte Ltd. 2020
Z. Luo and S. N. Khanna, Metal Clusters and Their Reactivity,
https://doi.org/10.1007/978-981-15-9704-6_1
1
An Overview of Metal Clusters and Their
Reactivity
Atomic clusters containing a few to a few thousand atoms are emerging as a frontier
area in science. The properties in this size regime are controlled by the discrete
quantum conditions associated with reduced size as opposed to bulk where the
properties are insensitive to the boundaries. Consequently, the physical, electronic,
magnetic, and chemical properties are all found to change with size and in many
cases, the properties at small sizes are different from those of bulk. Due to quantum
effects, the addition of a single atom or an electron can lead to a completely different
behavior. Consider the case of gold. Bulk gold is a noble element that is resistant
to corrosion. Yet, small gold clusters are found to be excellent catalysts where the
activity is highly dependent on the size. Bulk rhodium is non-magnetic while small
rhodium clusters are found to exhibit large spin magnetic moments. The novel behaviors have led to the expectation that it should be possible to design materials with
controlled properties by assembling size-selected clusters as the building blocks.
While the field of clusters can be traced to the formation of C 60 clusters as existed in
intersteller matter, the recent interest is inspired by the development in experimental
techniques over the past four decades that have enabled synthesis and characterization
of atomic clusters of finite size and any composition. In this book, we will primarily
focus on clusters of metallic elements. These clusters bridge several interdisciplines
by combining ideas within atomic, molecular and condensed matter with nuclear
physics, chemistry, and biology [1–6]. Several amongest research topics in metal
clusters, including structure and stability, size-dependent evolution and electronic
behavior, thermal property, catalysis and reactivity etc., have been widely investigated
[7–14]. In particular, techniques such as flow tube reactors coupled with quadrupole
mass spectrometers, and a combination of quadrupole and octupole fields in a guided
ion beam arrangement have been used in studies of cluster reactions, which are retrospect to about 40 years ago [15–25]. In recent years, extensive research interest has
been stimulated by ligand-protected metal clusters [26–33], showing novel structural
diversity and potential applications in catalysis, photochemistry, chemo-sensing, and
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Singapore Pte Ltd. 2020
Z. Luo and S. N. Khanna, Metal Clusters and Their Reactivity,
https://doi.org/10.1007/978-981-15-9704-6_1
1