3- Quantization of Light / Energy / Charge Flashcards
Short Wavelength =
High Energy
High Frequency
Long Wavelength
Low Energy
Low Frequency
Define “quantum”
Minimum, indivisible amount of physical entity or interaction
If excitation caused by absorption of a photon, then the radiative relaxation of the atom always emits a ….
… lower energy photon than was absorbed.
If there are no dipole-dipole allowed transitions, then…
phosphorescence.
Rayleigh-Jean Theory
Energy density distribution is proportional to λ^(-4)
Two properties of an ideal blackbody:
1) Absorbs all incident radiation (no reflection)
2) Re-emits radiation to environment
Discovery of the electron:
J.J. Thompsons Cathode Ray experiment
Discovery of the quantization of electric charge:
Millikan Oil-Drop Experiment
The Ultraviolet Catastrophe
Every object would have infinite energy density.
At very long wavelengths the Rayleigh-Jeans equation agrees with the experimentally determined spectral distribution, but at short wavelengths this equation predicts that u(λ) becomes large, approaching infinity as λ–>0
Experimental data suggests the distributions –>0 as λ–>0.
Quantized / Particle nature of light
Discovered by Hertz
Developed by Einstein
In developing the photoelectric effect, Einstein assumed…
…that the energy quantization used by Planck in solving the black- body radiation problem was, in fact, a universal characteristic of light.
Classical failures that led to photoelectric effect:
Classical theory says that k(max) is proportional to Intensity.
Quantum theory then tells us that intensity had no effect on k(max) only wavelength and k(max) is proportional to frequency. Thus, higher intensities gave us more ejected electrons.
bremsstrahlung
breaking radiation
electromagnetic waves produced by the acceleration of the electrons when they are deflected and stopped by the atoms of a target
- Photon-matter interaction
The (1) photoelectric effect, (2) the Compton effect, and (3) pair production are the three ways of interaction.
