Surface science is the name given to the challenging and complex interdisciplinary field that is focused on the physical and chemical interactions that occur at the interface between two phases: solid-liquid, solid-gas, solid-vacuum, liquid-gas, and so on. The terms ‘surface’ and ‘interface’ are used almost interchangeably when defining the boundary between two dissimilar phases. However, a distinction does exist:
- The term ‘interface’ can be explained as ‘the border between two spatial regions occupied by materials in different states’, i.e. the juncture at which two solids, or a liquid and a solid meet.
- The term ‘surface’ can be used to explain the interface between matter and air/a vacuum.
In consequence, surface science studies focused on solid materials are typically conducted under controlled vacuum conditions. Arguably, the development of modern surface science techniques is fundamentally linked to the introduction of high and ultra-high vacuum (HV/UHV) processes.
This article explores the applications and fundamentals of surface science and focusses on HV/UHV studies.
A Short History of Surface Science
The 1970s saw the first emergence of surface science, as an intertwined discipline of chemistry and physics. This followed significant breakthroughs in the process of depositing of gaseous species onto metallic substrates.
In 1974, the adsorption of hydrogen on palladium was first described by the Nobel Prize-winning chemist, Gerhard Ertl. Ertl’s research unlocked new understandings of heterogeneous catalysis, as well as propelling studies of surface chemistry into a new epoch of quantitative observation. Ertl’s research provided new insights into commercial, academic and industrial processes, and arguably laid the foundations of modern surface science.
Despite Ertl’s work, the history of surface science can be said to stem back even further. In the absence of high-purity vacuum conditions, it can be extremely complex and sometimes impossible to precisely and correctly undertake the study of the physics and chemistry of solid surfaces. In his revolutionary research on hydrogen adsorption, Ertl used low-energy electron diffraction (LEED): a technique discovered in 1927, nearly fifty years before his work.
This technique of LEED was initially considered not to be suitable for surface science-related applications, given that it used a collimated beam of low-energy electrons to observe diffraction patterns and intensities of electrons reflected off surfaces. Each of these was subject to interference from incident molecules within the process atmosphere. To put it simply: to reach the heights of academic viability, LEED needed better vacuum techniques.
A corner was turned in the 1960s, regarding high-vacuum technologies. This revolution effectively unlocked a new pressure regime for both academic research and industrial processing: namely, the ultra-high vacuum range, which reaches below 10-9 mbar. This development within the field was essential to Ertl’s research and has retained its significant impact on the wider field of surface science.
Surface Science: Nanoscale Chemistry and Physics
The field of surface science extends across a wide range of academic fields, with both commercial and real-world research applications. The science of surfaces continues, undertaken by researchers who explore it under HV/UHV conditions to illustrate both the physical and chemical characteristics of many and varied materials, to offer insights into properties as diverse as the below:
- Electronic and optical
- Quantum phenomena
A better understanding of technologies and materials at the atomic level has been provided by analyzing these interfacial properties. Such work has proven itself vital, not least in the development of clean fuel cells, 2D materials, quantum computing, new ecological processes, thin-film structures, monomolecular materials, new ecological processes, organic photovoltaics, and plenty more.
HV/UHV Components for Surface Science Applications
Allectra offers high-technology solutions to engineering and scientific markets, with a catalog of HV/UHV components that are optimized for surface science applications.
They have a strong product development history, as well as cutting-edge areas of research. Allectra is prepared to collaborate on tailored product resolutions according to your vacuum requirements.
This information has been sourced, reviewed and adapted from materials provided by Allectra Limited.
For more information on this source, please visit Allectra Limited.