[1] He was awarded the Lenin Prize in 1972 for a series of work titled "Elementary processes and non-elastic scattering at nuclear collisions".

He graduated with an undergraduate degree in physics from Leningrad State University in 1938, and remained there until the end of World War II.

Staying in the city, he then moved to the Ioffe Physico-Technical Institute in Leningrad, where he obtained his PhD in 1947 under Yakov Frenkel's supervision.

Firsov is known among physicists for his studies of the quasi-molecular approach in the quantum mechanical theory of atomic collisions.

In a 1951 paper, he presented an elegant analytical solution to the complicated problem of resonant charge exchange during hydrogen-hydrogen collisions.

At the beginning of the 1950s, when work on controlled fusion reactions had just started at Kurchatov, solving the problem of charge exchange for the confinement of a plasma in a magnetic system was crucial.

This formula has not only found a wide range of application in the physics of ion beams and radiation effects, but has also stimulated considerable theoretical activity.

He had particularly close scientific links with the experimentalist Vera Yurasova, with whom he also worked in the Russian Academy of Sciences Council for Plasma Physics.