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Stochastic electrodynamics (SED) without spin, denoted as pure SED, has been discussed and seriously considered in the literature for several decades because it accounts for important aspects of quantum mechanics (QM). SED is based on the introduction of the nonrenormalized, electromagnetic stochastic zero-point field (ZPF), but neglects the Lorentz force due to the radiation random magnetic field Br. In addition to that rather basic limitation, other drawbacks remain, as well: i) SED fails when there are nonlinear forces; ii) it is not possible to derive the Schrödinger equation in general; iii) it predicts broad spectra for rarefied gases instead of the observed narrow spectral lines; iv) it does not explain double-slit electron diffraction patterns. We show in this short review that all of those drawbacks, and mainly the first most basic one, can be overcome in principle by introducing spin into stochastic electrodynamics (SEDS). Moreover, this modification of the theory also explains four observed effects that are otherwise so far unexplainable by QED, i.e., 1) the physical origin of the ZPF, and its natural upper cutoff; 2) an anomaly in experimental studies of the neutrino rest mass; 3) the origin and quantitative treatment of 1/f noise; and 4) the high-energy tail (∼ 10 21 eV) of cosmic rays. We review the theoretical and experimental situation regarding these things and go on to propose a double-slit electron diffraction experiment that is aimed at discriminating between QM and SEDS. We show that, in the context of this experiment, for the case of an electron beam focused on just one of the slits, no interference pattern due to the other slit is predicted by QM, while this is not the case for SEDS. A second experiment that could discriminate between QED and SEDS regards a transversely large electron beam including both slits obtained in an insulating wall, where the ZPF is reduced but not vanished. The interference pattern according to SEDS should be somewhat modified with respect to QED's.

A review of the relevant data concerning the decay properties of the Cu þ fluorescence in alkali halides is presented. A critical analysis of the experiments reported in literature shows that the problem of the correct and complete interpretation of the Cu þ fluorescence was made complicated in the past essentially because of historical reasons. The validity of the decay models was ascertained by the authors by simultaneously detecting both lifetime and quantum yield during each set of measurements as a function of the temperature.

(ricevuto il 21 Febbraio 1991; revisionato il 18 Luglio 1991; approvato il 29 Luglio 1991) Summary. --A review of acquisitions and of unresolved problems concerning Fcentres in alkali halides is presented. The main conclusions are a) the temperature dependence of the bands is mainly due to the thermal expansion for the absorption process and to electron-phonon interaction for the emission process: for the latter half-width and Huang-Rhys factor values are related to the transverse optical frequency ones; b) the lifetime VR of the relaxed excited state is not intrinsic at low temperature because of the interaction between F-and a-centres always present in real samples; c) even though the absolute quantum yield decreases when F-centre concentration increases, the relative quantum yield vr is unaffected by change on F-centre concentration, strongly evidencing a nonhomogeneous distribution of F-centres in real samples; d) a temperature-dependent fine structure in zR (an Vr) values is observed but only when temperature control of the samples is better than a few hundredth of a degree: this effect has been interpreted in terms of interactions which involve F-, a-and F'-centres. PACS 61.70 -Defects in crystals. PACS 61.70.Dx -Colour centres.