X rays bombarding heavy atoms can be used
to eject electrons from the 1s shell in atoms;
indeed, this is the starting point for Moseley’s
experiments.
Estimate the maximum wavelength of pho-
tons required to eject an electron from the 1s
shell of copper, for which Z = 29. Planck’s
constant is 6.63 × 10−34 J · s and the speed of
light is 3 × 108 m/s2.
Answer in units of nm
1/λ=R(Z-1)²(1/n² - 1/m²)
R=1.1•10⁷ m⁻¹
Z=29
n=1
m=∞
1/λ=R(Z-1)²=1.1•10⁷•28².
λ=3.25•10⁻⁹ m.