An important contribution, with the British physicist
Ralph Fowler in 1928, was to establish the correct physical explanation of the physical phenomenon now called
field electron emission. They established that electron emission occurred by a form of
wave-mechanical tunneling, now called
Fowler–Nordheim tunneling, and, with the help of the assumption that electrons in metals obeyed
Fermi–Dirac statistics, derived an (approximate) emission equation. Over time, this equation has been developed into a family of approximate equations (offering different degrees of approximation to reality, when describing field emission from bulk metals), known as
Fowler–Nordheim-type equations. Fowler–Nordheim tunneling was the first effect in physics to be firmly identified as due to wave-mechanical tunneling, in the early days of quantum mechanics. The original Fowler–Nordheim-type equation was one of the first to use Fermi–Dirac statistics to explain an experimental phenomenon involving
electrons in metals, and its success greatly helped to establish modern electron
band theory. The Fowler–Nordheim paper also established the physical basis for a unified treatment of field-induced and
thermally induced electron emission. The ideas of
J. Robert Oppenheimer, Fowler and Nordheim were also an important stimulus to the development, by
George Gamow, and
Ronald W. Gurney and
Edward Condon, later in 1928, for the theory of the
radioactive decay of nuclei (by
alpha particle tunneling). ==References==