In physics, Planck's law describes the amount of energy emitted by a black body in radiation of a certain wavelength (i.e. the spectral radiance of a black body). The law is named after Max Planck, who originally proposed it in 1900. The law was the first to accurately describe black body radiation, and resolved the ultraviolet catastrophe. It is a pioneer result of modern physics and quantum theory.
For a given black body temperature, the wavelength at the peak of the Planck curve is called maximum lambda. This value gives a fell for the minimum relative size that an radiating object must be to optimally support photons associated with a give temperature. Like and antenna, a particle of nickel will best support the photons at a given temperature if the particle size is the adjusted to the ideal size. For a temperature of 700k or about 400C, the Lambda(max) must be 4.14 microns. This is why Rossi uses very large micro sized nickel particles in his reactor. Nano sized particles will not properly support the ideal photon wavelength needed to force protons into quantum mechanical coherence. Rossi undoubtedly found this optimal size through trial and error but science is easier. For a Planck function Infrared Radiance Calculator see the following: https://www.sensiac.org/external/resources/calculators/infrared_radiance_calculator.jsf%3bjsessionid=D08873244D6904EE654DBCDF0391F95E
