Absorption Definition and 534 Threads

I've heard that atomically bound electrons can potentially "absorb" an incoming photon, whereas a "free" electron has no such potential. Why is this? Also, can rapidly alternating un-bound electrons emit photons?

why is enerygy absorbed if the frequency of the radiation matches the frequency of the vibration?

Can anyone send me a picture of graph absorption spectra of 2,3-dimethylindole? The graph should be accurate (from a spectrophotometer) Thanks

How does work the two-photon absorption ? Does it exist a Beer-Lambert law for this kind of process? If yes, does someone know where i could find the order of magnitude of two-photons absorption coefficient for silicon at 1500 nm ? Barth

How do an atom "know" when to absorb a photon, and when not to? It seems like an atom absorbs all photons that either has energy that corresponds to the difference between two energylevels, or has any type of energy at all in which case the photon energy helps speed up the atoms oscillations...

I'm a little confused, we have tested chemical concentrations based on how much light it can absorb. What i don't understand is why something can have a reading of 60% transmission yet also have an absorption of 22.2% via the equation A = LOG(1/T), T being tranmission, A being absorption. Seems...

I've been wondering about absorption of oral drugs and their "therapetic" levels in the body/brain with regards to daily dosages. (I am particularly interested in SSRIs, if that makes any difference.) (I realize there are many factors that influence this. I'd like to get an idea of the ideal...

Is there a formula to determine how much absorption of a radio wave will occur in a plasma? Does radio wave absorption depend on the pressure and temperature aside from the electron and ion density?

Sir, Why can’t a free electron absorb a photon of energy completely?

I heard and read that mercury and some of its compounds can get absorbed through the skin how could it do that ? Aren't our skins soposed to be waterproof ? I don't think that while washing our hands with water the water pases through the epidermis.

Question. Does a stream of Electrons emitted in a Hard Vacuum Diode absorb light? If so what is the absorption Frequency? This Question is intend for only mean free Electrons in a Hard Vacuum. I have been wanting to emit some different LASER Frequencies into a Vacuum Diode and see if...

This question has really left me puzzled. I have no clue on how to go about. How do I show that a Photon can never be completely absorbed by an electron?

I'm supposed to find the answer to this in a short video but no matter how many times I listened to it, I couldn't find the second answer (Got the first easy enough though.)... What three things affect the growth of phytoplankton? So, I decided to try to look the answer up myself. Is this...

If photons are emitted or absorbed when a pair or a collection of particles, that are or behave as dipoles, undergo oscillation by some driving force, are there any systems that do NOT use a single or collective dipole oscillation to emit or absorb a photon?

for this question: calculate the mass and linear absorption coefficients of air for Cr K(alpha) radiation. Assume that air contains 80 percent nitrogen and 20 percent oxygen by weight and has a density of 1.29*10^(-3) g/(cm^3) my problem: i have no idea where to start.

In my understanding, when a nuclei absorbes a photon with the right freq it changes its spin... now, if this atom is in a magnetic field B on the Z direction, its magnetization vector is precessing around the Z direction, and after absorbing a photon it changes its angle relative to the Z axis...

Why don't stellar spectra show absorption lines for carbon, oxygen or nitrogen if they are such abundant elements. Is there a 'spectral type' that does? Thanks Dave

If IR rays at the appropriate frequency are passed through a vaporized sample of an alkane, will the vibrations induced be converted into thermal energy? If yes, then will the process take a substantial amount of time (on the order of seconds)?

A read of the COBE and WMAP teams' papers on the methods they used to produce 'contamination-free' maps (or, to remove all 'foregrounds') is exhilarating. However, unless I missed it, these methods largely address emission in the wavelengths of interest (i.e. those which the various...

When a photon hits an atom it gets absorbed and an electron moves one or more shells up depending on the energy of the photon. When a bigger, many-electron atom gets hit by a photon, can the electrons in the lower shells get excited? I mean when they move up they have to remove the electrons in...

Nereid brought up the subject of quasar absorption lines in the "Dark Matter" post. I worked on the subject as an undergrad, so I would be happy to answer any questions you have about it. Some examples of things it tells us are 1) The power spectrum of matter in the universe (small scales)...

I am having major trouble trying to figure the concentration of a substance that is given by the AAS. Here's the question: To determine the iron content in a 'Milo' milk drink, a 5ml sample was diluted to 50ml. the absorption of the diluted solution and of several standard solution were...

O.K. HOw much heat is absorbed by a person's hand if steam at 100degree C is first converted to liquid water at 100 degree C and then cooled to normal body temperture? I'm not sure of the formula for this one.

1) What percentage of incident photon radiation passes through 5 mm of material whose absorption coefficient is 0.7 mm^-1? What is an absorption length? I am lost here. Any input ...some mathematical formula for the absoprtion coefficient...would be a great help to me. 2) Why is the mean...

On standardized tests, it is often advised that one should eat an energy bar during breaks to get a boost of energy. But does a person really get a boost of energy during the test? Doesn't food take several hours to digest? Also - is it the small intestines that absorb all the nutrients...

Hi everyone, I was wondering (while in the shower of all places) whether photon absorption by an electron is a physical process or a mathematical consequence. That is, does an electron literally "eat up" the photon at the quantum level or is it just some consequence of the math that we give...

Is it possible to have solar panels one over the other with little space between them to get 10 panel stacked structures to increase the amount of solar energy absorbed? There are four solar panels. Another 4 on top of them leaving some space between this four and the bottom four. In the...

It has been mentioned in one of the other forums that different materials absorb different sound frequencies, and a suggestion was raised to use that for material analysis. Is this sort of testing actually being done? If so, what information can be found about the material this way?

hello all i'm investigating the band gap of certain nanocrystallites in the powder form, using a Shimadzu spectrometer with the powder dissolved in ethanol. The spectra, however, come with several peaks in addition to the expected peak for absorption. This is not unexpected as transitions to...

The Doppler effect corresponds to a percieved change in the wavelength of impinging light, correct? Does this mean that the Absorption spectra we would see for bodies in relative motion to light sources should be the same independent of the type of motion between the body/source (assuming that...

Can someone explain what absorption cross section is and how it's figured into an equation? And what is irradiation?

Ok, here's the question. Without the greenhouse gases in Earth's atmosphere the temperature would be 250K. With them it is 40K higher (290K). Using the Stefan-Boltzman equation for flux ( F = σT4) what is the percentage of infrared radiation leaving the Earth's surface taht is...

Hi, I need images of absorption and emission spectra for sodium to be used in a physics student book. Thanks in advance Stanley

I'm interested in engeeniring molecule with specific max. e-m wave apsorption. How to, where from to start ? eg. Like one used for blocking UV rays (btw do you have formulas of these molecules).