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Bill Madden 559 2123. = ( 4 /3ħc ) n e m 2 ( N m -N n ) ( o - ) 1 2 3 4 Square of the transition moment n e m 2 Frequency of the light Population difference ( N m - N n )
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= (4/3ħc) nem2 (Nm-Nn) (o-) 1 2 3 4 • Square of the transition moment nem2 • Frequency of the light • Population difference (Nm- Nn) • Resonance factor - Dirac delta function (0) = 1
Fermi’s Golden Rule = (4/3ħc) nem2 (Nm-Nn) (o-) 1
Take Home Message n*md nm ~ d/dq Quantum Mechanics Matrix Mechanics Dirac Notation Quantum Mechanics Wave Mechanics Schrödinger Notation Classical Analogue Dipole moment change over motion …coordinate q
Take Home Message n*md nm ~ d/dq ~ Quantum Mechanics Matrix Mechanics Dirac Notation Quantum Mechanics Wave Mechanics Schrödinger Notation Classical Analogue Dipole moment change over motion …coordinate q
= (4/3ħc) nem2 (Nm-Nn)(o-) 1 2 3 4 • Square of the transition moment nem2 • Frequency of the light • Population difference (Nm- Nn) • Resonance factor - Dirac delta function (0) = 1
For pure rotational transitions a molecule must have a permanent dipole moment
Observing the dipole change from the side i.e. the direction of propagation
∆N =? Selection Rules Harry Kroto 2004
(Nm- Nn) Nm-Nm
J 2J+1 e-∆E/kTNm/No F(J) 0 1 1.000 1.00 3.84 • 3 0.9812.94 7.69 • 50.9454.73 11.5 3 70.8936.25 15.4 • 90.8287.45 19.2 • 110.7548.29 23.1 • 13 0.6738.75 26.9 • 150.5908.85 30.8 • 170.5078.62 34.6 • 190.4288.13 38.4 • 22 0.355 7.46 42.3 • 230.288 6.62 46.1 • 250.230 5.75 50.0 Nm = No e-∆E/kT In the case of degenerate levels such as rotational levels eacj J level is 2J+1 degenerate we get Nm = Noe-∆E/kT
0 1 2 3 4 5 6 7 J 0 2B 4B 6B 8B 10B 12B 14B 16B Boltzmann
J 2J+1 e-∆E/kT Nm/No F(J) 0 1 1.000 1.00 3.84 • 30.9812.94 7.69 • 50.945 4.73 11.5 3 70.8936.25 15.4 • 90.8287.45 19.2 • 110.7548.29 23.1 • 130.6738.75 26.9 • 150.5908.85 30.8 • 170.5078.62 34.6 • 190.428 8.13 38.4 • 22 0.3557.46 42.3 • 230.2886.62 46.1 • 250.2305.75 50.0 Nm = No e-∆E/kT In the case of degenerate levels such as rotational levels eacj J level is 2J+1 degenerate we get Nm = Noe-∆E/kT
0 1 2 3 4 5 6 7 J 0 2B 4B 6B 8B 10B 12B 14B 16B Boltzmann
J 2J+1 e-∆E/kT Nm/No F(J) 0 1 1.000 1.00 3.84 • 3 0.981 2.94 7.69 • 5 0.945 4.73 11.5 • 7 0.893 6.25 15.4 • 9 0.828 7.45 19.2 • 11 0.754 8.29 23.1 • 13 0.673 8.75 26.9 • 15 0.590 8.85 30.8 • 17 0.507 8.62 34.6 • 19 0.428 8.13 38.4 • 22 0.355 7.46 42.3 • 23 0.288 6.62 46.1 • 25 0.230 5.75 50.0 Nm = No e-∆E/kT In the case of degenerate levels such as rotational levels each J level is 2J+1 degenerate we get Nm = No(2J+1)e-∆E/kT
0 1 2 3 4 5 6 7 J 0 2B 4B 6B 8B 10B 12B 14B 16B Boltzmann
+ - Positronium
n m Einstein Coefficients
H 21 cm Line Harry Kroto 2004