????????????????%20Bohr

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???????????????? Bohr
?????????????????????????????? ?
?????????????????????????????????
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???????????????? Bohr ? ???????????????????????
????????????????????????????????????????
????????????????????????????????????????? ??????
???????????????????? ?????????????????????????????
Bohr ???
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??????????????????????????
r
q
f
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???????????????????????????????????????
??????????????????????????????????????????????????
??
???????? ?????????????????????????????????????????
??
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Principal Quantum Number n
Orbital Quantum Number l
Orbital Magnetic Quantum Number ml
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• ?????? multiple-electron atom ???????????????????
  ??????????????????????????????????? 4 ?????????

• n (the orbital of main shell, n 1 (K), 2(L),
  3(M),),
• l (the orbital of subshell, l 0(s), 1(p), ,
  n-1 for a given n, ??? ???????? l n),
• ml (the same subshell with different
  configurations, ml -l,,0,,l for a given l,
  ??????????? ml 2l1 )
• ms (spinning state ?,?).
• The Paulis Exclusion Principle No two
  electrons in an atom have the same set of values
  for the four quantum numbers, n, l, ml, ms.

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The Paulis Exclusion Principle
???? ?.?. 1986 Dmitri Mendeleev
?????????????????????????? ???????????????????????
????????? ??????? Pauli ???????????????? The
Paulis Exclusion Principle
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The Paulis Exclusion Principle ????????????????
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1s Orbital
Subshell
(s l 0)
The region where an electron in 1s orbit is most
likely to be found.
According to QM
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2s and 2p Orbitals
2s
(s l 0)
2px
2py
2pz
2p ((p l 1) 3 different configurations (ml
-1,0,1)
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3d Orbitals
(d l 2)there are five different
configurations corresponding to ml -2, -1, 0,
1, 2
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???????
Light Amplification by Stimulated Emission of
Radiation

• Monochromatic ??????????????????????
• Coherent ????????? ?????????????????????????????
  ????????????????????????
• Directional ?????????????????????????
• High intensity ???????????????????????????
  ???????????????

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Coherent and Incoherent Lights
Comparison Lights and Lasers
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Absorption and Emission of Photons
??????????????????????????????????????????????????
?????? ?? ????????????????????????????????????????
???????????????????????????????????????????
exited state ??????????????????????????
??????????????????????????????????
?????????????????????????????? random
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Stimulated Emission of Photons
??????????????????????????????????????????????????
??????? (?????????????????????????)
??????????????????????????????????????????????????
???????????????? exited state ??????? ground
state ????????????????????????????????????????????
???????????????????????????????
Laser Generation
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A Population Inversion

1. ??????????????? ?????????????????????????????
   ground state ????????????????????
2. ??????????????????????????????????????????????????
   ?????????? ???????????????????????????????????????
   ??????????????????? ???????? population inversion

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Basic Operation of a Laser
A population inversion
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Lasers
So what do you need to build a laser?
1. Gain Medium - a material with atoms that have
a metastable state and that can achieve
population inversion
2. Excitation Source - a way to supply energy to
excite the atoms
3. Resonating Cavity (Mirrors) - allows the
stimulated photons to travel back and forth
through the gain medium so they can stimulate
more photons (light amplification)
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full mirror
partial mirror
gain medium

• allows some photons to escape to produce beam

• solid
• liquid
• gas

Laser in Cavity
Photon Emission
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X-Rays
???? Photons ???????????????????????? 100eV ???
100,000eV. ???????????????????????????????????????
??? (??????????????????????????).
????????????????????
0.01 nm to 10 nm
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??????? X-Ray
?????????????????????????????? 100 eV ???????????

• Black Body Radiation
• ?????????????????????????????????????????? 10
  ????
• Outer shell electrons falling in to 1s state
• ????????????????????? 10 eV
• Radioactive Decays
• ???????????????

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• ?????????? e- ????????????????????? 100,000 eV
  ????? heavy atoms
• e- ??????????????????????? Brehmsstrahlung
  ??????????????????????????????????????????????????
  ? e- ????????
• ?????? e- ??????????? 1s e- ??????????????????????
  ????? Characteristic X-Rays

VIS
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Characteristic X-Rays
Characteristic x-ray nomenclature n1 K
shell n2 L shell
n3 M shell
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Ka Example
Estimate the energy of Ka X-rays off of a silver
(Ag) target (Z47).
Not bad!
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???????????? X-Ray

• Continuous X-ray ???????????????? Bremsstrahlung
• ???????????????????????????????
• Characteristic X-ray ??????????????????????
• ??????????????????????? Photoelectric effect
• ???????????????????????????? X-ray
  ???????????????????????????????