Surface science

Overview
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid-liquid interfaces, solid-gas interfaces, solid-vacuum interfaces, and liquid-gas interfaces. It includes the fields of surface chemistry and surface physics. . Some related practical applications are classed as surface engineering. The science encompasses concepts such as heterogeneous catalysis, semiconductor device fabrication, fuel cells, self-assembled monolayers and adhesives. Surface science is closely related with Interface and Colloid Science. Interfacial chemistry and physics are common subjects for both. Methods are different. In addition, Interface and Colloid Science studies macroscopic phenomena that occur in heterogeneous systems due to peculiarities of interfaces.

History
The field of surface chemistry started with heterogeneous catalysis pioneered by Paul Sabatier on hydrogenation and Fritz Haber on the Haber process. Irving Langmuir was also one of the founders of this field, and the scientific journal, Langmuir, on surface science bears his name. The Langmuir adsorption equation is used to model monolayer adsorption where all surface adsorption sites have the same affinity for the adsorbing species. Gerhard Ertl in 1974 described for the first time the adsorption of hydrogen on a palladium surface using a novel technique called LEED. Similar studies with platinum, nickel followed. Most recent developments in surface sciences include the 2007 Nobel Prize of Chemistry winner Gerhard Ertl's advancements in surface chemistry, specifically his investigation of the interaction between carbon monoxide molecules and platinum surfaces.

Surface chemistry
Surface chemistry can be roughly defined as the study of chemical reactions at interfaces. It is closely related to surface functionalization, which aims at modifying the chemical composition of a surface by incorporation of selected elements or functional groups that produce various desired effects or improvements in the properties of the surface or interface. Surface chemistry also overlaps with electrochemistry. Surface science is of particular importance to the field of heterogeneous catalysis.

The adhesion of gas or liquid molecules to the surface is known as adsorption. This can be due to either chemisorption or by physisorption. These too are included in surface chemistry.

The behaviour of a solution based interface is affected by the surface charge, dipoles, energies and their distribution within the electrical double layer.

Surface physics
Surface physics can be roughly defined as the study of physical changes that occur at interfaces. It overlaps with surface chemistry. Some of the things investigated by surface physics include surface diffusion, surface reconstruction, surface phonons and plasmons, epitaxy and Surface enhanced Raman scattering, the emission and tunneling of electrons, spintronics, and the self-assembly of nanostructures on surfaces.

Analysis techniques
The study and analysis of surfaces involves both physical and chemical analysis techniques.

Several modern methods probe the topmost 1-10 nm of the of surfaces exposed to vacuum. These include X-ray photoelectron spectroscopy, Auger electron spectroscopy, low-energy electron diffraction, electron energy loss spectroscopy, thermal desorption spectroscopy, ion scattering spectroscopy, secondary ion mass spectrometry, and other surface analysis methods included in the list of materials analysis methods.

These purely optical techniques can be used to study interfaces under a wide variety of conditions. Reflection-Absorption Infrared, Surface Enhanced Raman and Sum Frequency Generation spectroscopies can be used to probe solid-vacuum as well as solid-gas, solid-liquid, and liquid-gas surfaces.

Modern physical analysis methods include scanning-tunneling microscopy (STM) and a family of methods descended from it. Two of these are atomic force microscopy (AFM) and SPM. These microscopies have considerably increased the ability and desire of surface scientists to measure the physical structure of many surfaces. This increase is related to a more general interest in nanotechnology.