130 likes | 138 Vues
Learn about the photoelectric effect, for which Einstein received the Nobel Prize, and how it led to the development of photoelectron spectroscopy (PES). Discover how PES can provide valuable information on atomic structure through spectroscopic data analysis.
E N D
A little history • Einstein earned the Noble Prize for his work on the Photoelectric effect. • The photoelectric effect is when electrons are emitted from a solid liquid or gas when they absorb energy in the form of light. • This has been determined experimentally by shining light on metal.
Photoelectric EffectBy shining a light on metal, one may create a current
Photoelectric effect • Increasing the intensity of the light increased the number of photoelectrons, but not their maximum kinetic energy • Red light will not cause the ejection of electrons, no matter what the intensity! • A weak violet light will eject only a few electrons, but their maximum kinetic energies are greater than those for intense light of longer wavelengths!
Photoelectron Spectroscopy • PES provides a useful means to extract information on atomic structure using spectroscopic data. • By looking at the data chart one may determine the structure of the atom. • How? The chart gives evidence for the shell model.
The method used can remove electrons from inner shells, leaving outer shells intact.
In Words • MNN Are artifact from the measuring device. • 3s electrons are removed in the 534 eV • 3p are removed at 673 eV • 3D are the most impressive at 335. • Near zero are the 5s and 4d valence electrons. These do not require much energy to be removed.
How to read the peaks? • The size of the peak tells you the relative number of electrons. • The position on the energy portion of the spectrum tells you the energy required to remove the electrons.
Pod Cast • https://www.youtube.com/watch?v=NRIqXeY1R_I