1. Photoelectron Spectroscopy (PES)  A data source that confirms the shell/subshell model of the atom  High-energy light (X-rays or short wave UV) ejects electrons from the atom  By measuring kinetic energy of the particles, we can derive the existence of different sublevels in the atom

2. Image Source: SPECS GmbH, http://www.specs.de/cms/front_content.php?idart=267 Photoelectron Spectroscopy

3. 3+ X-ray or UV Source X-ray or UV Source Kinetic Energy Analyzer Binding Energy (MJ/mol) 6.26 0.52

4. Kinetic Energy Analyzer Negative Voltage Hemisphere Slightly Less Negative Voltage Hemisphere

5. Negative Voltage Hemisphere Positive Voltage Hemisphere If Kinetic energy is too high… Negative Voltage Hemisphere Slightly Less Negative Voltage Hemisphere

6. Negative Voltage Hemisphere Positive Voltage Hemisphere If voltage is too high… Negative Voltage Hemisphere Slightly Less Negative Voltage Hemisphere

7. 3+ 5+3+5+3+ 5+ 3+5+3+5+ 3+5+3+5+ 3+ 5+3+5+ 3+5+ 3+ 5+3+ 5+ X-ray or UV Source X-ray or UV Source Binding Energy (MJ/mol) 19.3 0.80 1.36 Boron 6.260.52 Li Kinetic Energy Analyzer

8. Photoelectron Spectroscopy (PES)  A self-paced PES online professional development webinar is available for free on AP Central.  http://media.collegeboard.com/digitalServices/s wf/ap-webcasts/chemistry/ap_chem_pes.html http://media.collegeboard.com/digitalServices/s wf/ap-webcasts/chemistry/ap_chem_pes.html

9. Shells and Subshells Activity  In small groups, work through the activity sheets together  If your group finishes early, see if you can write an assessment question (or two) involving PES data  spectra can be found on the Arizona site or in the Dropbox