What is Absorption: Definition and 531 Discussions

Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum.
Absorption spectroscopy is employed as an analytical chemistry tool to determine the presence of a particular substance in a sample and, in many cases, to quantify the amount of the substance present. Infrared and ultraviolet–visible spectroscopy are particularly common in analytical applications. Absorption spectroscopy is also employed in studies of molecular and atomic physics, astronomical spectroscopy and remote sensing.
There are a wide range of experimental approaches for measuring absorption spectra. The most common arrangement is to direct a generated beam of radiation at a sample and detect the intensity of the radiation that passes through it. The transmitted energy can be used to calculate the absorption. The source, sample arrangement and detection technique vary significantly depending on the frequency range and the purpose of the experiment.
Following are the major types of absorption spectroscopy:

View More On Wikipedia.org
Recent contents Top users
  1. S

    Packed tower problem (gas-liquid absorption)

    Hi everyone, I'm having a bit of difficulty with a packed tower problem I'm working on. Not too sure how things work around here so I'll just jump straight in... The problem is; A packed column continuously recovers acetone (component A) from air by absorption with water at 60 deg. F...
  2. S

    Absorption of energy from a photon?

    Hey guys, am studying light and matter at the moment. Was just wondering: 1. Assuming an atom requires 3.2 eV to transfer an electron to an excited state, if a photon of 3.3eV struck the atom, would it still be absorbed. If so, what happens to the remaining energy
  3. P

    How Kinetic Energy is Absorbed

    Hi everyone, Hope you can help me in the right direction cos the gods of the internet seem to be hiding info from me...well ok I just can't find it.. any ways... I am looking for some info or a brief explanation on how kinetic energy is absorbed. Thanks in advance for your help...
  4. B

    Heat absorption, IR - light - UV, differences?

    General query about heat absorption. We all know that something that is black both absorbs and radiates heat better. My question is how does this property vary across the spectrum, if at all, for different materials (if there is any difference?). For instance, a black painted car will heat...
  5. M

    Neutron absorption cross section

    Does anyone know anywhere where I can find reliable up-to-date cross section infromation? In particular I'm looking for the absorption cross section of Gadolinium-157 for thermal neutrons. Everywhere I look seems to give a different value ranging fro 70000barns up to 450000barns.
  6. C

    How does the photon absorption process work in atoms?

    What is the process through which photons are absorbed/emitted from an atom? Also... One of the threads i visited first was this: https://www.physicsforums.com/showthread.php?t=76246" Post number 11, the one by Zoobyshoe explaining what Claude meant by the rope analogy using a billiard...
  7. H

    Question about energy absorption

    Ok, so I just took part in this lab for my Kinesiology class and I am having a little trouble figuring out the answers. It is my first time on this board and was just wondering if anyone could help. Here is the scenario. Energy absorption is a critical component of injury prevention, in many...
  8. Loren Booda

    Absorption of oxygen: lungs' vs. other capillaries

    Is the surface area of the alveolar capillaries comparable to that of all other arterial capillaries?
  9. H

    Absorption and reflectance spectrums

    hey, just wondering, what's the relationship between absorption and emissions spectra (i.e. would they absorb and reflect the same wavelengths or complement wavelengths of radiation?) thanx, hechnal
  10. R

    Exploring Oxygen's Magnetic Dipole & Radiation Absorption

    How can the magnetic dipole of a molecule (Oxygen for example) affect radiation absorption?
  11. T

    Scattering Vs Absorption Crossection

    What is the difference between Scattering Crossection and Absorption Crossection in nuclear reaction crossection? Please help me for one numerical problem; "Arsenic As^{33}_{75} has an absorption cross section for thermal neutrons of 4.1 b and a scattering cross section of 6 b, its density...
  12. I

    Time scale of photon absorption in electron

    Does anyone know, when an electron in an atom is exited by absorbing a photon, how long does it take for the electron to absorb the entire energy of the photon? Does the time scale depend on the energy level? Thanks!
  13. N

    Extra Energy from Photon Absorption

    Quick question: when an electron absorbs a photon with MORE THAN enough energy to jump one energy level but not two, what happens to the extra energy the electron doesn't absorb? Thanks.
  14. P

    Thermodynamics heat absorption problem

    Homework Statement How much heat is absorbed in changing 2-kg of ice at -5°C to steam at 110.0°C? The Specific heats of ice, liquid water, and steam are, respectively, 2060 J/Kg x K, 4180 J/Kg x K, and 2020 J/Kg x K. The heat fusion of ice is 3.34 x 10^5 J/Kg. The heat of vaporization of...
  15. I

    Photoinduced absorption spectroscopy

    I'm trying to comprehend a paper I'm supposed to summarize this one: ---ok it won't let me post urls---- whatever My question, is what is the deal with photoinduced absorption spectroscopy? I gathered that it involves a "pump" (burst of light) striking the sample and then a "probe"...
  16. S

    Can I Determine Unknown Sample Concentration Using Absorption Spectroscopy?

    Hi I'm trying to measure the concentration of a sample dissolved in water. I'm using the spectrometer USB4000 which directly gives me the absorbance value. Using beer-lambert law is there a way i can determine the unknown sample concentration from this measurement? I have the values 'A' and...
  17. E

    How Does Optical Absorption Threshold Measure the Band Gap in Semiconductors?

    [SOLVED] direct absorption proces Homework Statement My solid-state physics book (Kittel) says the following in the chapter about semiconductors: "In a direct absorption process the threshold of continuous optical absorption at frequency \omega_g measure the band gap E_g = \hbar \omega_g"...
  18. A

    Photon Absorption: Does Energy Matter?

    If a photon does not have the required energy for changing the quantum state of a particle/atom/molecule, is it absorbed and instantaneously re-emitted with the same energy when it arrives at said particle/atom/molecule or is it not absorbed at all? Also, does it make any difference in...
  19. D

    Optical absorption in Semiconductors

    [SOLVED] Optical absorption in Semiconductors Homework Statement I'm doing a lab report on the optical absorption of semiconductors. More specifically it was to determine the bandgap values of the semiconductor samples. This is the experimental setup...
  20. B

    Absorption of Nutrients from Drinking Blood

    If a person ever drinks blood, what nutrients and stuff from drinking that blood would be absorbed into their bloodstream?
  21. S

    Absorption of Photons question

    [SOLVED] Absorption of Photons question Radiation of equal intensities of 0.3 A X-rays (Ua=0.3 1/mm) and 0.5 A x-rays (Ub=.72 1/mm) are incident on a material. Find the thickness of the material if, in the emerging radiation, the 0.3 A x-rays are twice as intense as the 0.5 A x-rays. The...
  22. S

    Absorption of Light and Energy Conservation

    Hello everybody. I apologize if this question is a little trivial compared to a lot of the threads posted, but I am an 8th grade science physical science teacher and am a little confused about some of the material. From what I understand, if an atom absorbs a photon of energy E, then an...
  23. O

    Absorption Spectra: How is a Continuous Spectrum Possible?

    erm a simple question. If all light comes from the electrom-photon interference in an atom, that means that we can't obtain a continuous spectrum theoratically. How then is an absorption spectrum possible??
  24. S

    What Distinguishes an Excitation Spectrum from an Absorption Spectrum?

    What's the difference between an excitation spectrum and an absorption spectrum for the same molecule? Are the words interchangeable, or are they completely different processes? In Sharma, A. and Schulman, S. G. (1999). Introduction to Fluorescence Spectroscopy. Wiley interscience, it says...
  25. R

    Absorption by Plants: Can a Plant Take in Water?

    A small plant is stripped off its leaves and is placed in a beaker containing water. The water surface is covered with oil to prevent evaporation of water. Will the plant absorb water within a couple of hours or so?
  26. D

    Absorption of photons by electrons

    Hi, my name is David. I'm a High School student in Virginia. I'm doing a research project that concerns controling the frequency and wavelength or energy of a photon that is "absorbed" and emitted by an electron. Here are some assumptions and questions I am working on. Any help would be...
  27. K

    Absorption Spectra - Questions & Answers from NZ High School Student

    Hello everyone, I'm new to this forum and in fact have never used a forum before so this is a bit new for me. I'm a high school student from NZ, and some of the course I'm doing has flummoxed -not in that I can't rattle off the generic answer, I just don't quite understand. The main area in...
  28. J

    Exploring Light Absorption & Reflection: How Much is Too Much?

    As I know, a black substance absorbs all light and a white substance reflects all light. Can I say, in a black substance, the electrons are in a high energy state, compared to a white substance? And how much light energy it can absorb? There has to be a limit to it, right? So, shouldn't a...
  29. G

    Food slows down the absorption of alchohol?

    Food slows down the absorption of alchohol?? 1. The presence of food in the stomach, particularly fats, greatly slows down the absorption of alchohol and drugs into the body. This what I've read in a report on the internet, but I don't know the reason why the rate of absorption slows down. Can...
  30. E

    Free-Free Absorption Coefficient: Intuitive Concept

    I am trying to form some intuitive concept about the free-free absorption coefficient for a hydrogen plasma. The standard expression (cf. e.g. Schwarzschild's Structure and Evolution of the Stars, 1958, p64) contains a reasonably familiar particle type cross-section component, but there is also...
  31. T

    Photon Absorption: Atom, Transition Level, and Energy

    All the while, I thought that an atom only absorbs a photon that precisely corresponds to one of the transition level (resonance), but now I read that the atom will also absorb photon with wavelengths different from the transition level in question. So, my question is, suppose I have two energy...
  32. Simfish

    Absorption of Food: Factors & Timeframes

    If people are advised to take an "energy boost", so to speak, they're advised to take in sugary substances. Yet, the thing is - all nutrients are absorbed through the small intestines. But does food stay in the stomach for a number of hours? And then, what factors control the passage of food...
  33. A

    Indirect absorption processes -

    Indirect absorption processes -- need help! On page 188-190 in Introduction to Solid State Physics by C. Kittel, I read I don't get it. I thought it was as simple as this: the highest point in the valence band and the lowest point in the conduction band have two different energies, and they...
  34. S

    To calculate absorption coefficient

    want to calculate absorption coefficient or absorption crosssection for 1% C2H2 gas Path length = 1meter Absorbene = 0.32 concentration = 8500ppm pressure = 1 atm Temperature = 25C I need to express this concentration to mol/cm3. Pls let me know if u have anyidea
  35. M

    Two photon absorption coefficient of silicon

    Hi, is there a way to calculate the two-photon absorption coefficient of silicon? I am especially interested in the two-photon absorption coefficient of silicon for the wavelengths 1030nm, 515nm and 343nm. Thanks for any help!
  36. S

    Atmospheric Absorption of Starlight

    I realize that Starlight atmospheric absorption depends on frequency, but I was wondering if there are any tables indicated total bolometric absorption at Zenith relative to absorption at Sea Level. Obviously atmospheric absorption is much less on the top of Everest than in my hometown (a few...
  37. G

    Atoms Energy Emission, Absorption

    I was wondering about the process of atom excitement/ionization. If you have a atom that has 4 energy levels and a emitted photon from a laser that had the wave characteristics (F,L,E) as not the valance electron, but the sub shell below the valance electron (match the sub shell energy gap), can...
  38. M

    Help with an absorption drying tower

    Can I just say that anyone willing to offer help I will pay them £20+ an hours for their time, I could only really see this happening over msn real time chat though, but I will publish findings on this site. I am studying chemical engineering and am having trouble with a problem, I am only...
  39. G

    Fourier absorption spectra of Carbon monoxide

    So I have a spectra of CO that I need to interpret. My guess is that the spectra will depend on the vibrational and vibrational factors but how could I see that? I mean what will that come out like in the Fourier spectra? any tips on this our a site where I can read more about it is...
  40. L

    Photon absorption by an accelerated atom

    I'm wondering whether QM considers photon absorption by an accelerating atom as an instantaneous event, or the change in velocity (and proper time) of the atom affects the perceived distribution of the wave packet and the outcome of the process. In other words, is there a "Doppler gradient"...
  41. C

    Spectroscope: dark absorption lines

    Why are Absorption lines dark? I don't really understand the spectroscope and how it works... Can anyone help me out with this theoretical question? No math involved! Thanks.
  42. L

    Absorption Coefficient of Aluminium

    Hi. I am new here! I'm doing a experiment on the absorption of beta radiation of aluminium and I need help! :redface: Does anyone know what the absorption coefficient of aluminium? Or at least where I can find it. Thanks in advance! o:) P.S. Sorry if I've posted in the wrong part of the forum...
  43. K

    Hydrogen Atom Emission and Absorption

    QW Why does the emission from hot hydrogen atoms consist of the Lyman, Balmer and Paschen series but the absorption of cold hydrogen atoms consists of just the Lyman series? is it because the cold hydrogen atoms absorb characteristic frequencies and the lyman series involves transitions that...
  44. S

    Rate of Heat Absorption from Visible vs Infrared Light

    I recently did an experiment with the Crookes's Radiometer. The radiometer was first placed under a 100W 1600 lm bulb and then a 100 W 2360 lm bulb. Though they both emit the same energy, the radiometer spun about 30% faster under the 2360 lm. Why is this? I was thinking maybe this was...
  45. Z

    Calculating Energy Absorption of 2.0kg Bag of Ice

    A 2.0 kg bag of ice is used to keep a cooler of pop cold for 5.5 h. If the ice had an initial temperature of -4ºC and, after 5h, was liquid water with a temperature of 3ºC, find the power of energy absorption. Any help would be great. I don't know where to start:confused:.
  46. B

    Time Elapsed between Light Emission and Absorption at Different Frames

    A flash of light is emitted at point O and is later reabsorbed at point P. In frame S, the line OP has a length l and makes an angle theta with the x axis. In a frame S' moving relative to S with a constant velocity v along the x axis: How much time tau' elapses between emission and absorption...
  47. K

    The Color of Water: Exploring Wavelengths & Dissipative Absorption

    I cannot understand what is the colour of water.I was reading an Optics book by Hecht,& suppose that we see coluured bodies due to Dissipative absorption.That is taking up of incident photon,converting a part into thermal energy,and releasing the rest energy as another photon.But, ordinarily we...
  48. P

    Free/Bound Electrons and Photon absorption

    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?
  49. A

    Absorption of radiation at vibration frequency

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

    Graph absorption spectra of 2,3-dimethylindole?

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