October 1st, 2003
Spectroscopy
Prisms Diffraction gratings
Transmission grating Reflection grating
d sin n and n 1, 2, 3, ...
nN
nN
Resolving power
Spectral Lines Photons The Bohr Model of the Atom Quantum Mechanics and Wave–Particle
Duality
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
RH
109677.585 0.008 cm1
1
RH
1 m2
1 n2
and
mn
Planetary model of the hydrogen atom?
m=1 m=2 m=3 m=4 m=5
UV [122, 103, 97, …] nm Visible [656, 486, 434, …] nm IR [1875, 1282, 1094, …] nm IR [4051, 2625, 2165, …] nm
A cool, diffuse gas in front of a source Байду номын сангаасf a continuous spectrum produces dark spectral lines (absorption lines) in the continuous spectrum.
NJIT Center for Solar-Terrestrial Research
Physics 320: Astronomy and Astrophysics – Lecture V
Carsten Denker
Physics Department Center for Solar–Terrestrial Research
NJIT
The Interaction of Light and Matter
Proton: mp = 1836 me
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
Group Assignment Problem 5.7
Verify that the units of Planck’s constant are the units of angular momentum!
Compton Effect
Ephoton
h
hc
pc
f
i
h 1 cos
mec
Compton wavelength
c
h mec
0.0243 ?
In a collision between a photon and an electron initially at rest, both the (relativistic) momentum and energy are conserved.
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
Photoelectric Effect
Ephoton
h
hc
Kmax
Ephoton
h
hc
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
L mvr
kg
m s
m
=
kg
m2 s
E h h E
J
s-1
=
Js
=
Nm
s
=
kg
m s2
m
s
=
kg
m2 s
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
Hydrogen Atom
1
RH
1 4
1 n2
and
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
The Bohr Model of the Atom
Wave–particle duality of light
Rutherford 1911 Au: It was quite the most incredible event that ever happened to me in my life. It was almost as incredible as if you fired a 15–inch shell at a piece of tissue paper and it came back an hit you. discovery of a minute, massive, positively charged atomic nucleus
A hot (< 0 K), dense gas or solid object produces produces a continuous spectrum with no dark spectral lines.
A hot, diffuse gas produces bright spectral lines (emission lines).
William Wollaston, Joseph Fraunhofer, Robert Bunsen, Gustav Kirchhoff, … spectroscopy
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
Kirchhoff’s Laws
Electromagnetic Spectrum
NJIT Center for Solar-Terrestrial Research
October 1st, 2003
Spectral Lines
Auguste Comte 1835 in Positive Philosophy: We see how we may determine their forms their distances, their bulk, their motions, but we can never know anything of their chemical or minerological structure.