Ultraviolet photoelectron spectroscopy (PES), a method based on the photoelectric effect, is used to measure ionization energies. Electrons are emitted by illuminating monochromatic light onto a sample then the kinetic energy of the emitted electrons is measured. The ionization energy (energy needed to eject the electrons) is the difference between the energy of the photons and the kinetic energy of the electrons. Assume that a PES experiment is conducted in which xenon gas is illuminated with 102.3 nm. Identify the halogen whose initial ionization energy is closest to xenon.
Ionization Energy: Fluorine = 1681 kJ/mol, Chlorine = 1251 kJ/mol, Bromine = 1140 kJ/mol, Iodine = 1008 kJ/mol