I've been asked to calculate the ionisation energy of hydrogen, which I've worked out at 1310 kJ/mol (to 3sf).

I now have to calculate the ionisation energy of deuterium.

I've been given the Rydberg constant (R infinity) = 109737.3 cm^-1

Since the mass of deuterium is twice the mass of hydrogen, would the ionisation energy of deuterium just be twice the value of the ionisation energy of hydrogen? (since E and m are linearly related)?

*EDIT. Or does the ionisation energy of H = ionisation energy of D, due to them having the same electrostatics? Similar to the isotope effect?