Fritz Haber's surface idea inspired Langmuir

Person: Fritz Haber
Lived: 1868–1934
Field: Chemistry
From: German

The story

Adsorption, the sticking of gas or liquid molecules to the surface of a solid, is the basis of catalysis, filters and many industrial processes. In the early twentieth century scientists were still trying to understand why surfaces attract molecules at all.

Fritz Haber, born in 1868 into a Jewish family in Breslau, was by then one of Germany's leading physical chemists and, from 1911, director of the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry in Berlin-Dahlem. Catalysis on surfaces was central to his most famous achievement, the synthesis of ammonia, in which nitrogen and hydrogen react on the surface of a solid catalyst.

Haber suggested that the adsorbing power of a solid body can be due to unsaturated valence forces: chemical bonding capacity left over at the surface, where atoms are not fully surrounded by neighbours and so still have bonds to offer.

According to his Nobel biography, the American chemist Irving Langmuir founded his theory of adsorption on this observation. Langmuir, working at the General Electric research laboratory, presented his model in 1916. He proposed that a surface has a fixed number of equivalent sites to which molecules can stick, and that gas molecules do not bounce off a surface elastically but are held by it much as molecules are held together in a solid. The model predicts how much gas covers a surface at a given pressure, with a single layer one molecule thick as the limit. Langmuir received the Nobel Prize in Chemistry in 1932 for his discoveries in surface chemistry.

Surface science is now listed among the fields for which Haber is known. In his last years he worked on chain reactions, the mechanisms of oxidation and the catalysis of hydrogen peroxide. His institute in Dahlem, renamed the Fritz Haber Institute in 1953, counts surface chemistry and surface physics among its research fields. Gerhard Ertl, who worked there and whose research helped explain the surface catalysis at the heart of the ammonia process, received the Nobel Prize in Chemistry in 2007.

Why it matters

Understanding why surfaces grip molecules underpins modern catalysis, gas separation and filtration, technologies used across the chemical industry and in cleaning air and water.

About Fritz Haber

Nobel chemist whose ammonia synthesis made the fertilisers that feed billions, who also led Germany’s WWI poison-gas programme, and who was driven out by the Nazis.

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Fritz Haber

1868–1934 · Chemistry

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