what is the difference between a bright-line spectrum and an absorption spectrum?

Answer 1

A pattern of dark lines or bands superimposed on a continuous spectrum. When a continuous spectrum of radiation (a broad range of wavelengths) passes through a material medium (for example, a cool, low-pressure gas), selective absorption occurs at certain particular wavelengths. This gives rise to a series of dips in intensity (absorption lines) which, in the visible region of the spectrum, appear as dark lines against the bright background of the ‘rainbow’ band of colors that comprises the continuous spectrum. Photons of electromagnetic radiation may be absorbed through radiative excitation, a process that occurs when an electron in one of the lower energy levels of an atom or ion absorbs a photon with energy precisely equal to the difference in energy between that level and one of the higher permitted levels and, as a result, jumps (makes an ‘upward transition’) from the lower to the higher level. Because the energy of a photon is inversely proportional to wavelength, the larger the energy gap, the shorter the wavelength of the radiation that is absorbed when an electron makes a particular transition. An electron does not normally remain in an excited level for long (typically 10−8 s). When it drops down again, it emits a photon or photons that may or may not have the same wavelength as the one that was originally absorbed (depending on whether it drops directly to its original level or descends in a series of smaller steps). If it drops in a series of steps, each of which corresponds to the emission of a photon of lower energy (and longer wavelength) than the one thatwasoriginally absorbed, the total number of photons of the original energy will be reduced and the spectrum will be depleted at the input wavelength. Furthermore, although all the input photons were traveling along essentially the same direction (from the source to the observer), the re-emitted photons travel away in random directions. Consequently, far fewer photons at the absorption wavelength reach the observer than photons of other wavelengths. The resulting absorption line is darker than the adjacent part of the continuous spectrum but, because some photons of that wavelength do reach the observer, not totally black.
Because each permitted transition corresponds to absorbing light of one particular wavelength, atoms or ions of a particular element produce absorption lines at a number of different wavelengths, each chemical element having its own distinctive ‘fingerprint’ pattern of absorption lines. The shortest-wavelength lines correspond to the largest energy gaps (i.e. to transitions from the lowest, or ‘ground’, level of the atom or ion). If an electron absorbs a photon with energy in excess of the ionization energy (or ‘ionization potential’), it will be removed from the atom. The absorption spectrum of a particular species of atom consists of several series of lines, corresponding to the various permitted transitions, the short-wavelength limit of the series corresponding to the photon energies above which ionization takes place. Because ionizing photons can, in principle, have any value of energy above the ionization energy, absorption can take place over a continuous range of wavelengths, shorter than the series limit. Absorption of this kind is called an absorption continuum. The prominence (‘strength’) of any particular line depends on the number of atoms of the appropriate chemical element that have electrons residing in the energy level from which the relevant upward transition takes place (the degree of excitation). That, in turn, depends on the abundance of the particular chemical element (the relative proportion of that element in the absorbing substance) and on a number of other factors, in particular the temperature (the higher the temperature, the greater the proportion of electrons in excited states).
In addition to producing absorption through electronic transitions (like atoms and ions), molecules may also absorb (or emit) radiation by changing their states of vibration (their constituent atoms vibrate relative to each other) or rotation (a molecule, having a physical shape, can rotate about a particular axis). Molecular absorption spectra are complex, their various lines often merging into broader bands.

Answer 2

An absorption spectrum uses different wavelengths of lights to measure the absorbance of various solutions. A bright line spectrum, has the same process as well, I think.

Answer 3

Light is given off by material that has been heated. (normally)

When you look through a prism, or a spectroscope (which is just a glorified, and calibrated prism) it breaks up the light by wavelengths.

Certain elements produce, and absorb certain wavelengths. If you heat a particular element, that element gives off a bright-line spectrum. If you place a particular element between yourself and the light source, that element absorbs some of the light, and produces an absorbtion spectrum.

Suppose you're looking into space through the atmosphere of the earth: The atmosphere of the earth is composed of O2, O3, H20, CO2, N2, etc. Whatever source of light you look at from the earth will have the absorbtion lines of these gasses. If there are other absorbtion lines, or if the absorbtion lines are darker than usual, that means that your source of light has passed through some other material.

If the light you're looking at has really bright bands, these are bright line spectrums, and indicate that the hot part of the light source is made up of these.

Answer 4

Sorry guys, a bright-line spectrum is an emission spectrum, the opposite of an absorption spectrum. They can give you the same information. See

http://csep10.phys.utk.edu/astr162/lect/light/absorption.html

Answer 5

If you shine light through something cool enough not to be incandescent, like a planetary atmosphere, you get an absorption spectrum. That's how w first found out the composition of the planets'atmospheres. If you make something hot enough to ionise the outer electrons in its atoms, you get an emission spectrum, like when you sprinkle salt in a flame and the sodium makes it glow yellow.

Answer 6

i think the guy on top of me is right. studying for finals huh?