Optical properties of bivalent REM in liquid state

On the basis of the almost free electrons model the analysis of experimentally obtained data is performed for optical properties of liquid REM: neodymium, europium, ytterbium and gadolinium. The electrons participating in energy-level transition are divided into various groups. As this takes place the additivity of contributions from these groups of electrons into light transmission must be considered. The problem of determining partial values of additive functions is solved in a graphical representation through variational selection of three following parameters: a peak height, a peak position and a leak half-width-using the approximation method