Nikolay Nikolayevich Semyonov ForMemRS, sometimes Semenov, Semionov or Semenoff[1] (Russian: Никола́й Никола́евич Семёнов; 15 April [O.S.

During that difficult time, Semyonov, together with Pyotr Kapitsa, discovered a way to measure the magnetic field of an atomic nucleus (1922).

In 1931, he organized the Institute of Physical Chemistry of the USSR Academy of Sciences (which moved to Chernogolovka in 1943) and became its first director.

Semyonov's outstanding work on the mechanism of chemical transformation includes an exhaustive analysis of the application of the chain theory to varied reactions (1934–1954) and, more significantly, to combustion processes.

He proposed a theory of degenerate branching, which led to a better understanding of the phenomena associated with the induction periods of oxidation processes.

Some Problems of Chemical Kinetics and Reactivity, first published in 1954, was revised in 1958; there are also English, American, German, and Chinese editions.

He is also noted as being the most famous signatory to a 1971 public letter from Soviet scientists to United States president Richard Nixon, on displeasure in the murder trial of Angela Davis.

Semyonov trained Russian organometallic chemist Alexander Shilov, who discovered platinum catalyzed C-H activation.