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5.1. Photoelectron spectroscopy (UV-vis PES) Suggested Textbook Reading: Chapter 8, Section 8.8 • Molecules with valence electrons of binding energy < 40 eV can be ionized by

irradiating them with light of the right frequency. Typically a Helium lamp is used.

• The binding energy (BE) of an electron is found from the kinetic energy (KE) of the ejected electron and the photon energy hν.

hν = BE + KE + ΔEvib

ΔEvib = difference in vibrational energy between the ion and the original molecule

• The removal of an electron from an anti-bonding orbital:

Source: Ebsworth, Rankin, Craddock, "Structural Methods in Inorganic Chemistry", CRC Press, 1991.

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• The removal of an electron from a bonding orbital:

• The removal of an electron from a non-bonding orbital:

Source: Ebsworth, Rankin, Craddock, "Struct. Meth. in Inorg. Chem.", CRC Press, 1991.

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• Examples: N2 vs. O2

Ebsworth, Rankin, Craddock, "Structural Methods in Inorganic Chemistry", CRC Press, 1991.

Source: Shriver & Atkins, Inorganic Chemistry, 3rd ed., Freeman, 1999. Related Textbook Exercise 8.7