Thulium Ionization Energy

The Thulium Ionization Energy is the energy required to remove from atom one mole of electrons with subsequent production of positively charged ion of Thulium.
Tm -> Tm⁺ + e^-
This process can be repeated many times, but the energy cost is increased dramatically. The general equation for the Thulium is:
Tm^N+ -> Tm^(N+1)+ + e^-

Tm -> Tm¹⁺ = 596.7 kJ/mol = 142.75 Kcal/mol
Tm¹⁺ -> Tm²⁺ = 1163 kJ/mol = 278.23 Kcal/mol
Tm²⁺ -> Tm³⁺ = 2285 kJ/mol = 546.65 Kcal/mol
Tm³⁺ -> Tm⁴⁺ = 4119 kJ/mol = 985.41 Kcal/mol