Atomic Physics Flashcards
what does spectroscopy involve
the measurement of the wavelength frequency and energy of EM radiation
deBroglie equation
P=hbar(K) =h/lambd=hv/c
Absorption
a photon takes the atom from E_1 to E_2. A photon with energy deltaE = E_2 - E_1 = hv is removed from the radiation field
spontaneous emission
AN electron in a higher energy state de-excites to a lower energy state spontaneouslt emitting a phtoton of a specific energy E_if (I= intial energy state, f= final energy state) to the radiation field
what type of gas involve emission
hot gas, due to the atoms needing to be in a excited state
Bohr first postulate
Electronsmove in circular orbits about the nucleus under the influence of coulomb attraction, obeying classical mechanics.
what did Bohr’s first postulate show
the existence of the nucleus
Bohr’s second postulate
An electron can only move in an orbit for which its orbital angular momentum L in an integral multiple of hbar L=n(hbar)
what did Bohr’s second postulate show
it introduced quantisation
Bohr’s third postulate
The electron is stable in its orbit: constant energy E and does not radiate
What does Bohr’s third postulate show
It removes problem of stability (by stating that this law of classical mechanics does not apply)
Bohr’s Fourth postulate
Absorption and emission are possible through the movement of an electron between two stale orbits, a and b. Radiation frequency v of absorption / emission goes by : V_ab = (E_a - E_b)/h
what did Bohr’s fourth postulate show
Basically Einstein’s postulate v=E/h
n-fold degenerate
when the total energy of the electron onl depends on n
What four things did schordinger’s theory reveal about the properties of the atom
Probability density functions
orbital angular momentum
electron spin
transition rate
what are degenerate eigenfunctions
eigenfunctions corresponding to the same eigenvalue are degenerate
magnetic dipole in a non uniform field
a magnetic diploe in a non uniform field experiences a torque which will cause precession and a force which will cause displacement.
what will atoms experience in a uniform magnetic field
Zeeman effect
what will happen to atoms in a non-uniform field (what effect)
atoms undergo displacement due to the stern Gerlach effect
what is the Zeeman effect
The Zeeman effect is the splitting of atomic energy levels and the associated spectral lines that result when the atoms are placed in a magnetic field.
what did the stern Gerlach experiment show
The experiment showed, qualitatively,that the orientation of atoms in space is quantised.
space quantisation.
it showed that Schrödinger’s theory was not complete due to missing out electron spin.
Define total angular Momentum J
J = L + S
where J = total angular momentum
S = torque due to spin
L = orientation
Quantum defect
A quantum defect, δ(n,l)—a correction to the principle quantum number, n.
anomalous Zeeman effect
The splitting of some spectral lines did not occur as expected in a magnetic field.
normal zeeman effect
used to describe lines that split as expected. Ths splitting can be explained by the quantization of angular momentum.
3 Things about Normal Zeeman effect
- atomic systems with 0 total spin angular momentum
- applied magnetic field couples to the total orbital angular momentum - the levels split by an amount determined by a constant and the magnetic quantum number m
2 things about anomalous Zeeman effect
- occurs for atomic systems that have total sin angular momentum.
- This causes a different splitting ratio in different levels leading to the observation of more than three components to a transition
