Chapter 2
Quantum Mechanics – I
2.1 Basic Concepts and Formulae
Wave number
˜
ν =
1
λ
(2.1)
1 fm = 10
−15 m; 1 ˚
A = 10
−10 m; 1 nm = 10
−9 m; 1 μm = 10
−6 m; c =
197.3 Mev − fm
Photon energy
E = hv
(2.2)
Photon momentum
p = hν/c
Photon energy − wavelength conversion
λ(nm) =
1241
E(eν)
(2.3)
de Broglie wavelength
λ = h/ p
(2.4)
λ(electron) : λ( ˚
A) = (150/V )
1/2
(2.5)
λ(neutron) : λ( ˚
A) = 0.286 E
−1/2
(E in ev)
(2.6)
Atomic units
The Bohr radius
2
/m e e
2 is frequently used as the unit of length in atomic physics.
In atomic units the energy is measured in multiples of the ionization energy of
hydrogen atom that is m e e
4
/2
2 . In these units
2
= 1, e
2
= 2 and m e =
1
2
in
all equations.
87
Quantum Mechanics – I
2.1 Basic Concepts and Formulae
Wave number
˜
ν =
1
λ
(2.1)
1 fm = 10
−15 m; 1 ˚
A = 10
−10 m; 1 nm = 10
−9 m; 1 μm = 10
−6 m; c =
197.3 Mev − fm
Photon energy
E = hv
(2.2)
Photon momentum
p = hν/c
Photon energy − wavelength conversion
λ(nm) =
1241
E(eν)
(2.3)
de Broglie wavelength
λ = h/ p
(2.4)
λ(electron) : λ( ˚
A) = (150/V )
1/2
(2.5)
λ(neutron) : λ( ˚
A) = 0.286 E
−1/2
(E in ev)
(2.6)
Atomic units
The Bohr radius
2
/m e e
2 is frequently used as the unit of length in atomic physics.
In atomic units the energy is measured in multiples of the ionization energy of
hydrogen atom that is m e e
4
/2
2 . In these units
2
= 1, e
2
= 2 and m e =
1
2
in
all equations.
87