spectroscopy Flashcards
Temperature measure
the internal energy of an object
1st Law of Spectroscopy
A dense gas or solid produces a
continuous (blackbody) spectrum
a blackbody
- is a perf ect absorber of light at all wavelengths.
- reradiates that energy at all wav elengths as it warms up
- is described just by its temperature
The peak wavelength of a blackbody
depends inversely on its TEMPERATURE
Wiens law
Consequence of Wien’ sLaw
Hotter objects are BLUER
Cooler objects are REDDER
A star radiates like a blackbody. If its surface
temperature doubles, the w avelength of maximum
intensity w ill be ___ times the original w avelength
0.5
The energy output by a blackbody
depends only on its TEMPERATURE
Flux =
Power released per square meter [W/m2]
Stefan-Boltzmann Law:
The f lux f rom a blackbody depends
strongly on temperature:
Definition:
Flux = Power released per square meter [W/m2]
= Stef an-Boltzmann
constant
Consequence of Stefan-Boltzmann Law:
Hotter objects are Brighter* at All Wavelengths
Luminosity =
Total Power [Watts
find luminosity
Luminosity = Total Power [Watts]
Use the total surface area of the
star to find the energy emitted by
the star each second
The total power radiated (the luminosity)
depends on f lux and size
We measure the amount of red light given off by a red -
hot blackbody. When the blackbody is heated until it
glows bluish-white, the amount of red light it gives of
increases
Blackbody radiation is observed from three planets. A
peaks in the visible, B peaks in the infrared, and C peaks
in the radio.
Which planet is hottest
planet A
Hydrogen:
The Simplest Atom
one proton, one electron
Behav ior on atomic
scales is gov erned
by
quantum mechanics
One rule of quantum mechanics
Electrons can only exist on orbits of specific energy.
* mov e between by emitting or absorbing photons
2nd Law of Spectroscopy:
A hot, transparent gas produces
an emission spectrum
right emission lines.
* Darkness between the emission lines
Larger Jump =
= More Energy = Bluer Wav elength
Elements with more electrons have
more spectral lines
Emission lines
Emission lines are used to identify atoms (and molecules)
When an atom absorbs a photon
(li ght-w ave),
an electron moves from a lower energy level
to a higher energy level
3rd Law of Spectroscopy
A transparent gas, in front of a
hotter blackbody, produces an absorption spectrum.
Absorption Lines
produced when electron absorbs a photon with exactly the
energy needed to jump f rom a lower to a higher orbital
All stars produce dark line absorption spectra
Hot dense core,
surrounded by a low-
density outer atmosphere
A spectral emission line results from
electrons j umping to a low er orbit
