| dc.description.abstract | Light emitted from atoms during transitions of electrons from higher to lower discrete
states has the form of photons carrying energy and angular momentum. This paper considers the
process of emission of a single photon from the hydrogen atom by using quantum theory and
Maxwell’s equations [W. Gough, Eur. J. Phys. 17, 208, 1996; L. D. Landau and E. M. Lifshitz,
Quantum Mechanics (Pergamon Press, Oxford, 1965); J. D. Jackson, Classical Electrodynamics
(John Wiley & Son, New York, 1975, 1982); P. M. Morse and H. Feshbach, Methods of
Theoretical Physics (McGraw-Hill Book Company, Inc., New York, 1953)]. The electric and
magnetic fields of a photon arise from the time-dependent quantum probability densities of the
orbit and the spin current. This paper is an extension of the semiclassical description of
photon emission published by the author earlier in 1999 [M. Kowalski, Phys. Essays 12, 312
(1999)]. In the semiclassical approach, the Coulomb force and a radiation resistance force have
been taken into account to get time-dependent emission of the photon. In both the quantum and
semiclassical cases, the transition takes place within a time interval equal to one period of the photon’s
wave. The creation of a one-wavelength-long photon is supported by the results of experiments
using ultrafast (ultrashort) laser pulses to generate excited atoms, which emit light pulses
shorter than two photon wavelengths [F. Krausz and M. Ivanov, Rev. Mod. Phys. 81, 163 (2009);
H. Kapteyn and M. Murnane, Phys. World 12, 31 (1999)]. VC 2021 Physics Essays Publication.
[http://dx.doi.org/10.4006/0836-1398-34.2.116] | en |
