The light emission observed from small palladium particles during passage of electronic current

Light emission spectra were measured from separate Pd particles excited by the passage of electrical current through them. As the particle size decreases or input power increases the intensities of peaks increase more strongly in the high-energy part of the spectra than in the low-energy part. Moreover, new peaks can appear in the high-energy region. The color of an emission center changes from red to blue upon an increase in electric power fed into the Pd particle. This process is reversible and can be observed visually. On a further increase in feeding power, the Pd particle can be brought to a premolten state and can even melt. The integral intensity of light emission then increases dramatically, and the light emission spectrum changes and corresponds to thermal radiation. This latter process is irreversible.