Please enable JavaScript.
Coggle requires JavaScript to display documents.
AMO (Fine structure (∆E=-(aZ)^2/n*(3/4n-1/(j+1/2)) E_n (darwin-term :red…
AMO
Fine structure
rel. effects:
∆Erel=-E_n•(Za/n)^2•(3/4-n/(l+0.5))
§l, §a^4 (E_n§a^2)
-
-
ES: n=1,2, l=0,1,2=S,P,D
j=l+/-1/2
-
-
Experiments
Lamb-Retherford:
measure Lamb-Shift: j1=j2, l1!=l2
2S_1/2 not decaying => current
induce 2S_1/2->2P_1/2->decaying to 1S => current reduced at 1.05GHz
-
-
-
Atoms
Many electrons
each subshell L,S=0
"active e-" count
H=∑kin+pot+1/r_ij (ignoring spin)
central field approx: V_ZF=Z/r+S(r) spherical
=>SE separates: Hpsi=Epsi, psi=psi1*psi2..
+antisym psi ->Slater-determinant
Alkali-Atom
1 active e-
quantum defect (empirical description of spectrum)
weakest bound e-: E=-R_y*(1/(n-∂_l))^2
=>E&l: low l => close to nucleus :red_flag:
corrections to CF approx: residual+spin-orbit interaction
\(H=\sum_{i=1}^N[-\frac{\hbar^2}{2m}\Delta_{r_i}+V_{ZF}(r_i)+(\sum_{j>i}^N\frac{e^2}{4\pi\epsilon_0r_{ij}}-S(r_i))+c(r_i)\vec{L}_i\cdot \vec{S}_i]\)
Russel-Saunders Coupling (ignore S-O term)
ES are ES of L, S
obey angular momentum coupling (Clebsch-Gordons)
and Pauli-principle
ground state?
Hunds rules:
- max S -> min E (e same spin direction->less spatial overlap->less repulsionl
- if max S: max L -> min E
(same l => e meet less often)
- outer shell not full => min J
otherwise max J
-
H-Atom
solve SG:
- separate relative/ COM part
- separate angular/ radial part
E=-R_y*(Z/n)^2 not§ l,m
=> aber rel corr. => §l, ext field => §m
-
-
-
He-Atom
neglect red mass, masspolterm
H=kin1,2-pot1,2-intterm
ground state:
- neglect intterm (ind zi model): psi=psi(r1)+psi(r2)
- perturbation; <psi_1s2|1/r_12|psi_1s2> ∆E=5/4•R_y :red_cross:
-
excited state:
1.neglect intterm ->E=-Z^2•R_y (1/n1^2+1/n2^2)
- one close to nucleus(Z'=Z) one far (Z'=Z-1)
- exchange op: P_12 commutes with H
=> ∆E=direct±exchange integral: direct:repulsion, exchange=correlation: psiA(r1=r2=0->∆E lower
=> sym is ES
no two-fold excited helium =>above ionization threshold
spin: P_12->sym(triplett),antisym(singulett)
Pauli-Prinzip
-
-
Methods
Perturbation Theory
-
-
time-dependent H(t): two-state exactly soluble
otherwise: perturbation theory:
Dyson series
\(c_n(t)=c_n^{(0)}+c_n^{(1)}+c_n^{(2)}+..\)
Variational Principle:
estimate ground state arbitrary psi'
E'=<psi'|H|psi'> >= E_0
proof with psi'=∑c_n*psi_n
better: psi with minimization parameter l
-
Molecules
H2+
\(H=-\frac{\hbar^2}{2M}(\Delta_{R_A}+\Delta_{R_B})-\frac{\hbar^2}{2m}\Delta_r-\frac{e^2}{4\pi\epsilon_0}(\frac{1}{r_A}+\frac{1}{r_B}-\frac{1}{R})\)
-
-
notation
\(^{2S+1}|M_L|^{+/-}_{g/u}\)
+/- symmetry upon reflection of z
g/u space inversion
\(|M_L|=0,1,2..=\Sigma,\Pi,\Delta\)
-
-
Quantum Mechanics
-
coherent state
imitates class harm oscillator
defined by \(\hat a |\lambda\rangle = \lambda|\lambda\rangle\)
expressed in energy ES\(|\lambda\rangle=\sum_{n=0}^\infty f(n)|n\rangle\)
distribution is Poisson in n for mean \(\bar n=|\lambda|^2\)
\(|f(n)|^2=(\frac{\bar n^n}{n!})e^{-\bar n}\)
-
two-state system
time-dependent potential coupling the states
\(V_{12}=V_{21}^*=\gamma e^{i\omega t}\)
=> Rabis formula (if prepared in state 1)
emission absorption cycle
\(|c_2(t)|^2=\frac{\gamma^2\hbar^2}{\gamma^2\hbar^2+(\omega-\omega_{21})^2/4}sin^2([\frac{\gamma^2}{\hbar^2}+\frac{(\omega-\omega_{21})^2}{4}]^{\frac{1}{2}}t)\)
resonance condition:
\(\omega\approx\omega_{21}=\frac{E_2-E_1}{\hbar}\)
narrower resonance as \(\gamma\) (potential) small
-
-
-