Determination of neptunium electronic structure in fluoride compounds based on calibration of isomer shifts

Using calibration of isomer shifts in the framework of ion model, electron density on nucleus and populations of neptunium 5f-shell in fluorides NpF5, NpF5 and in hypothetical compounds NpF7 and NpF6+ are determined, possible values of isomer shifts being evaluated for the latter. It is shown, that the results agree well with the conclusions, which follow from relativistic MO calculations in the basis of free ions