An absorption line will appear in a spectrum if
an absorbing material is placed between a source and the observer
. This material could be the outer layers of a star, a cloud of interstellar gas or a cloud of dust. Incoming light (left) passes through a cloud of absorbing material, such as a cloud of interstellar gas.
What conditions produce an absorption line spectrum quizlet?
What conditions produce a dark (absorption line) spectrum?
Light from a continuous spectrum source passing through a cooler low-density gas.
How are absorption lines produced?
An absorption line occurs when
an electron jumps from a lower energy state to a higher energy state
, extracting the required photon from an outside source of energy such as the continuous spectrum of a hot, glowing object.
Why do different atoms have different lines in their spectra?
The lines in the spectra occur at wavelengths corresponding to photon energies exactly equal to the spacing of two energy levels in the emitting or absorbing atom. Different atoms have different lines
because the spacings of their energy levels are different
.
Which spectral type below has the strongest molecular absorption lines?
Hydrogen
lines are strongest in A stars with atmospheric temperatures of about 10,000 K. Ionized metals provide the most conspicuous lines in stars with temperatures from 6000 to 7500 K (spectral type F). In the coolest M stars (below 3500 K), absorption bands of titanium oxide and other molecules are very strong.
What can absorption lines tell us?
As photons fly through the outermost layers of the stellar atmosphere, however, they may be absorbed by atoms or ions in those outer layers. The absorption lines produced by these outermost layers of the star tell us a lot about
the chemical compositition, temperature, and other features of the star
.
What is the wavelength of the strongest hydrogen absorption line?
You would see the strongest hydrogen lines for a cloud that is at
about 9000 K
.
What do absorption lines mean?
An absorption line will appear in a spectrum if
an absorbing material is placed between a source and the observer
. Photons with specific energies will be absorbed by an atom, ion or molecule if this energy is equal to the difference between the energy levels. …
What is the smallest particle?
Quarks
are the smallest particles we have come across in our scientific endeavor. The Discovery of quarks meant that protons and neutrons weren’t fundamental anymore.
Which element has the most spectral lines?
Mercury
: the strongest line, at 546 nm, gives mercury a greenish color. Fig. 2. When heated in a electric discharge tube, each element produces a unique pattern of spectral `lines’.
What causes the dark lines in the absorption spectrum of an element to occur?
An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies;
since the re-emitted light is unlikely to be emitted in the same direction as the absorbed photon
, this gives rise to dark lines (absence of light) in the spectrum.
Which spectral type has the weakest hydrogen lines?
Spectral Types. Stars are divided into groups called spectral types (also called spectral classes) which are based on the strength of the hydrogen absorption lines. The
A-
type stars have the strongest (darkest) hydrogen lines, B-type next strongest, F-type next, etc.
Why do the coolest stars show weak Balmer lines?
If the surface of a star is as cool as the surface of the Sun (about 5800 K) or cooler, most of the atoms are in the ground state. … Again,
there are very few hydrogen atoms with electrons in the second energy level
, so the Balmer lines of these stars are weak.
What spectral class of stars is the coolest?
The spectral sequence is also a colour sequence: the O- and B-type stars are intrinsically the bluest and hottest; the
M-, R-, N-, and S-type stars
are the reddest and coolest.
Why does the sun’s corona show emission lines?
The corona
shines brightly in x-rays because of its high temperature
. On the other hand, the “cool” solar photosphere emits very few x-rays. This allows us to view the corona across the disk of the Sun when we observe the Sun in X-rays.
How do you calculate the number of absorption lines?
For example, suppose one atom with an electron at energy level 7 (n2=7). That electron can “de-excite” from n2=7 to n1=6,5,4,3,2, or 1. All those transitions give one spectral line for each. Thus, total of 1×6=n1(
n2−n1
) (foot note 1) spectral lines would be present in the spectrum.
