Abstract: | The well-known defects of the surface of a solid, microscopic projections and spikes, play a decisive role in electron emission
induced by an electric field. If there are mobile electrons of holes in the solid, then the electric field is enhanced by
a factor of 10–100 at the tip of a microscopic projection. This effect was discovered in electrostatics more than a century
ago. In turn, the probability of tunnel emission of an electron from a metal into a vacuum is an exponential function of the
electric field strength. Correspondingly the electron emission current density at the tip of a microscopic spike can be larger
than that on a smooth surface by an astronomical factor. This effect is particularly strikingly manifested when picosecond
pulses of infrared laser radiation of moderate power are used to initiate autoelectronic emission. Relative to a smooth surface,
the emission current density is enhanced by hundreds of orders of magnitude. These experimental conditions can be used to
scan the surface of a conducting material with a laser beam and to detect all the microscopic projections, in order to male
detailed observations with subpicosecond time resolution of the phase transition from autoelectronic emission to explosive
emission.
Polytechnic University, Tomsk. Institute of Electrophysics, Ural Branch of the Russian Academy of Sciences. French National
Scientific Center, Saclay, France. Translated from Izvestiya Vysshikh Uchenbnykh Zavedenii, Fizika, No. 11, pp. 42–44, November,
1997. |