On the maximum splitting of the (2F7/2) ground state in Yb3+-doped solid state laser materials

Using a scalar crystal field parameter, we show that the maximum splitting of 2F7/2 of Yb3+ can be quantitatively derived in a theoretical way from the maximum experimental splitting of Nd3+ in the same host. To the best of the authorʹs knowledge, it is the first time that the scalar crystal field theory is used to extrapolate results for a given ion to another one in the Lanthanide series. This is allowed by the new finding that the Lanthanide contraction causes the scalar crystal field parameter to contract linearly in a given host through the series with a slope increasing with the host crystal field strength. Since Nd3+ is less prone than Yb3+ to mixings with vibronics, this approach helps to distinguish the highest Stark level of 2F7/2 from vibronics, using the following prediction: The maximum splitting of the 2F7/2 Yb3+ ground state cannot be less than the one of Nd3+ 4I9/2 in any given crystal host.