2.5 Quantum Physics Flashcards
Photon
‘An indivisible packet of electromagnetic energy’
Quantised
‘Specific/whole integer number’
Electron volt, eV
‘The energy possessed by an electron which has been accelerated through a pd of 1V’
Work function
‘Minimum energy required to release and electron from the surface of a metal’
Threshold frequency
‘Minimum frequency a photon requires to release a photoelectron from a metal surface’
Ground state
‘Lowest possible energy level/stable level’
Energy level
‘an orbit with an energy where an electron can remain’
LASER
‘Light Amplification by the Stimulated Emission of Radiation’
Collimated
‘All parts travel in the same direction’
Population inversion
‘Achieving more electrons in an excited state than in the ground state’
Metastable state
‘An energy Level where an electron is stable for several magnitudes of time longer than a normal energy level’
Spontaneous emission
‘The spontaneous falling of an electron from a high to low energy level, with the emission of energy E2-E1 in a random direction’
Stimulated emission
‘A passing photon of the exact required energy causes an electron to fall from a high to low energy level. The falling electron emits a photon of the same energy and direction as the stimulating photon and has a constant phase difference’
CT
Computed tomography
Photon equations and planks constant value
E=hf or E=hc/¥
h=6.63x10^-34
EV equation and value
E=VQ
1eV=1.6x10^-19
Excitation causes
- Electron collision; -ionisation-excitation
- Incoming photon- must exactly equal difference between two levels
Relaxation explanation
-The electron configuration in an excited atom is unstable because a vacancy is left in the shell it moved from
-sooner or later, the vacancy is filled by an electron from an outer shell transferring to it. When this happens, the electron emits and photon
-the energy level of the photon js equal to the energy lost by the electron and therefore by the atom