What is Absorbtion: Definition and 59 Discussions

Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, which are repelled electrostatically.Neutron capture plays a significant role in the cosmic nucleosynthesis of heavy elements. In stars it can proceed in two ways: as a rapid process (r-process) or a slow process (s-process). Nuclei of masses greater than 56 cannot be formed by thermonuclear reactions (i.e., by nuclear fusion) but can be formed by neutron capture.
Neutron capture on protons yields a line at 2.223 MeV predicted and commonly observed in solar flares.

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  1. J

    A How to calculate the temperature change of a laser-irradiated material

    I am looking to approximately calculate the temperature change of a sample that was exposed to a laser pulse. Experimentally, we know the optical absorption, reflection, and transmission, as well as the source parameters for our laser system. I realize that I will have to make approximations...
  2. L

    Calculate number of photons absorbed

    I've tried to solve this by calculating the number of photons. I've done this by calculating the energy of one photon, taking h*c divided by lambda. h*c is 1240 eV*nm and lambda is 10 nm. This gives me 124 eV. I then divide the total energy by the energy of one photon, 50 keV/ 124 = 403 photons...
  3. J

    Understanding Light Reflection: Exploring Photons and Reflective Surfaces

    Simple question. Are photons reflected as is from a surface like a mirror, or is the reflecting surface atoms capturing the photons and re-emitting them?
  4. F

    I Understanding Gunn-Peterson through the Reionization epoch

    Into an extra-galactic physics course, I don't understand well the "Gunn - Peterson" effect on the spectrum of high redshift quasars (z greater than 3 or 4, up to the current limit of z = 6-7 I think) The observed fact is that there is an almost total absorption for the photons of the blue part...
  5. Z

    Carbon dioxide in liquid and gaseous phases with liquid water

    What are the differences between carbon dioxide solubility (miscibility, reaction) in liquid water when in gaseous (<38 bar) and liquid (>38 bar) phase? The temperature in my experiments is usually between 0 and 5°C. The stirring speed is around 500 rpm. Is the solubility given apart from...
  6. R

    Does water vapour absorbtion depend on H2O conc or RH?

    Hello If I blow air containing a fixed kg/m3 of water vapour over anhydrous CaCl2, will the absorbtion rate change if the air temp is different? To simplify, we neglect exotheric heat generated by hygroscopy. Thanks for your answers to this rather simple question.
  7. entropy1

    Photon absorbtion and conservation

    If a (polarized) photon is absorbed by a polarization filter, does its energy go into the filter? I am wondering if that is the case to obey conservation laws. And if it passes, is its original polarisation direction somehow conserved?
  8. R

    Neutron absorbed by a sheet of indium, % chance

    Homework Statement A neutron is passing through a thin sheet of 115In of thickness 0.01 cm. Given that the density of the sheet is 7.31 g cm-3 and that the absorption cross section is 100 barns, what is the chance of the neutron being absorbed? You may assume the neutron is not scattered. a)...
  9. O

    Resonance absorbtion of neutrons

    Hi, As you may know, the following equation gives the number of neutrons absorbed per cm3/sec in a resonance region. Fa=Φav∫∑a(E) dE So, it is said in Lamarsh, introduction to nuclear engineering, that Φav depends on temperature. I do not get this because I know that the flux is something we...
  10. K

    B What happens to absorbed colors in colored substances?

    They say that substances have color because when light waves of all colors hit the substance, the atoms do absorb all the colors, except those that is its color. Red substance is red because it absorbs all the color waves, but reflects the red waves. But all the color waves the red substance...
  11. Daniel Petka

    Can any object withstand the power of light?

    Every material absorbes some light, right? -even a mirror! So I ask myself: is there anything bigger than the wavelength of that light that cannot be destroyed with a powerful lightsource? (for example laser)
  12. S

    I Transmittance and Absorbtion of light

    I'm trying to understand the graph (attached) and if 'Z' is the absorptance or transmittance of amorphous silicon or CiGS, or the absorptance of ZnO. The bandgap of CiGs is between 1.1eV and 1.7eV. ZnO has a bandgap of 3.3eV, so any photon energy below that will not be absorbed. The 'Z' part...
  13. I

    I Transient Absorbtion Spectroscopy

    Hello there! The picture attached in file shows typical spectrum of transient absorption spectroscopy. Is it possible to have the same components in quantum dots?
  14. ChrisVer

    How to Calculate Hemolysis Percentage from Absorption at a Given Wavelength?

    How can someone calculate the hemolysis (%) from the absorption at λ wavelength given some concentration in NaCl? The formula I saw was really weird: Absorb(most hypotonic solution) = 100 % hemolysis I canlt understand that formula though... thanks
  15. praveena

    About atmosphere light absorbtion

    Hi pf, I am having a basic doubt.Even this may be a silly question.sorry for that.While in the morning due to sun's light we can able to see our atmosphere and also clouds.But at night even when we foccused a large amount of light towards the space. why can we able to see the atmosphere...
  16. Rodwen

    Light absorbtion and change in temperature of liquids

    Hi hi, Sorry if this is awful and boring. Basically what I want to work out is a way to differentiate two different liquids by touch (specifically, temperature) after shining a light on them. A thermometer cannot be used. The variables open here are the compositions of the liquid (I'm going...
  17. marcis

    Optics problem --- absorbtion index

    Hello I have an optic problem I want to calculate absorbtion index I know transmittance by 90% ;refraction index to material 1.586 ; thickness 2 mm ; power of source 21 lm
  18. H

    Exploring Absorption of EM Quanta: The Truth About Microwaving Chocolate

    I started out with a video of someone "measuring" the speed of light by microwaving a chocolate bar. Not surprisingly, this turned out to be partially bogus. http://morningcoffeephysics.com/measuring-the-speed-of-light-with-chocolate-and-a-microwave-oven/ This sparked some more questions...
  19. N

    Absorbtion coefficent and radiation curve

    Homework Statement I have data of an experiment to find absorbtion coefficent of a sample. one curve shows intensity of original beam, the other one is intensity with sample (with wavelenght). Here is the data : Homework Equations Where: I = the intensity of photons transmitted across...
  20. A

    Fourier Series and Absorbtion questions?

    I have to do a science fair, and I am really interested in physics. I spent forever trying to think of a topic, and I got myself stuck doing something with waves. After weeks of thinking of an expirement that will compete well without being extremely difficult, I came up with one. Does using...
  21. P

    Definition of transient absorbtion

    Hi, could someone help me to define what is transient or in other words short-lived absorbtion? Maybe the general defintion could sound something like: In transient absorbtion the sample is excited with some kind of source(electrons, laser ,x-ray and so on) and then flashed with wide spectra...
  22. P

    Conventional absorbtion spectra and E_g

    Hi, I have measured conventional absorption spectra of semiconductor - Optical density from wavelenght. So now I want to evaluate band gap for this material. In what kind of coordinates I how to reperesnt this spectra to see the band gap value ( where graph crosses the Energy axis) ? *I m...
  23. P

    Δp for total reflection and absorbtion of E&M radiation explanation?

    The equation for the change in momentum for total absorption of electromagnetic radiation is ΔU/c and that for total reflection is (2ΔU)/c. How could the momentum of electromagnetic radiation change if it is massless and travels at a constant speed c? Is the ΔU just a representation of a change...
  24. M

    Bicycle seat post shock absorbtion.

    Hi i am currently studying a bicycle seat post suspension unit. It is one of the lower end of the range models which consists of a spring and a rubber dampener. Basic outline in cad below. http://imageshack.us/a/img407/1720/drawing1layout1.th.jpg I would like to know the calculations behind...
  25. D

    Energy of a photon emission or absorbtion

    Homework Statement When energy is absorbed is the E value negative and when the energy is emitted is the E value positive? Homework Equations E=hf=E1-E2 (Is this equation correct for noth emision and absorbtion or just absorbtionbecause this is what my textbook says) E=-13.6/n^2...
  26. J

    Energy level after photon absorbtion

    Say a photon was absorbed by an electron at 1s in an oxygen atom but it only had enough energy to move it to another energy level that was already occupied such a 2s etc. What happens to this photon?
  27. T

    Medical Does CO2 and HCO3- inhibit N2O absorbtion into the blood?

    I'm asking because I want to know whether the technique of rebreathing N2O back into a balloon reduces the the amount absorbed when inhaled again. It obviously dilutes the N2O with some CO2 and water vapor, but I assume the dilution is pretty minimal.
  28. S

    The relationship between absorbtion, emissivity and reflection

    As I understand it, the absorption coefficient of a surface of material is the same as its emissivity (due to Kirchoff's law of thermal radiation), and that the net of this and the tranmissibility is emissivity + reflectivity + transmissibility = 1 Is this a general statement about...
  29. C

    Salt absorbtion from the ocean

    I have checked with doctors and even some molecular biologist and can't get a solid answer. I like to wade fish in the ocean and I have Menieres disease. I have to really watch salt in my body. If I fish waist deep in the ocean for 5 or 6 hours a day will the skin allow salt to enter the...
  30. A

    Can Steel Replace Concrete Plynths for Vibration Absorption in Motor Support?

    Hi, So I'm on a work term during a semester off at school (Mechatronics), and have been asked to see if it is feasible to replare some concrete plynths with steel. These are used to support a motor and, possibly, some excentrically rotating masses. My problem is that I don't really know...
  31. S

    Absorbtion of light- a dillema

    I am fascinated light and how its phenomena are possible, however one particular area in which there is slight doubt in my mind is in absorbtion, after reading both online and in books 2 conflicting theories on this. The first idea is that a photon of light which has the correct amount of...
  32. J

    How Can I Identify Elements in Jupiter's Absorption Spectrum?

    I've recently taken a spectral image (visible wavelengths) of Jupiter. After calibrating my spectral analysis program I've been able to get wavelength per pixel and produce a graph of intensity vs wavelength. I have an absorption spectra of Jupiter, but I am unaware on how to correlate which...
  33. J

    Odor absorbtion of baking soda

    I do not understand why baking soda is a good absorber of odors. Is it like activated charcoal or something? The reason I ask is because I have patch of odor in my carpet and someone suggested sprinkling baking soda on it. I just do not see this working. Also I have a carpet cleaning machine so...
  34. A

    Absorbtion lines in spectrum question

    shining white light through a gas of a vapourised element causes absorbtion lines to be created in the white light spectrum ie. there are dark lines running through the otherwise continuous spectrum and the position of these lines are unique to particular element. Why is it though that we...
  35. L

    Transmission, reflection, and absorbtion

    In order for us to see something, the light photon needs to be reflected, not absorbed or transmitted? Then is it that the same frequency of visible light keeps falling on something, an apple is always red in white light, why does it reflect red?
  36. S

    Question on absorbtion spectra

    An atom has energy levels En=-\frac{A}{n^2} where n is an integer and A is a constant. Among the spectral lines that the atom can absorb at room temperature are two adjacent lines with wavelengths 97.5 nm and 102.8 nm. Find the value of the constant A in electron volts. Initially I thought we...
  37. J

    Why do some materials reflect and others absorb light?

    If the question was that why are some materials opaque and why some are transparent, the answer would be found in the energy bands. If energy bands allow such transitions for electrons, that they can absorb photon, then they will absorb it, and the photon does not go through the material. If...
  38. A

    Photon absorbtion by free electron

    About a year ago a member here made a post regarding this subject title - I found this post/forum through a google search looking for this very bit of information... this is my *first* post, so please forgive my ignorance with forum etiquette. :) Firstly, I am not a physics major, doctorate...
  39. I

    Absorption & Emission: What Causes Electrons to Excite?

    I seem to have some trouble finding a definite answer by searching the following: It is my understanding that when an electron is excited to a higher energy state, it will spontaneously decay back and emit a photon. My questions are: Is the wavelength of light required to excite an...
  40. P

    Modeling the Absorbtion of Silver-doped glass

    Hi all, I'm doing some theory for my research, and I'm stuck! I'm trying to figure out why the absorption spectrum peaks at 420nm for silver nanoparticles. I know that this is expected for silver--I understand conceptually what's going on... but am trying to show it mathematically. I'm...
  41. Topher925

    Why does a polyimide coating prevent water absorbtion in silica fibers?

    In order to prevent water from being absorbed into a silica based optical fiber, a very thin coating of polyimide (polyamide) is often applied to the outer cladding. This works very well to prevent water from penetrating into the hydrophilic silica. But polyimide is very hydrophilic as well...
  42. V

    Absorbtion of kinetic energy or momentum

    IF you throw metal or wood or whatever material ball into soft bed then it almost do not reflecting from bed as you can try. So where goes such ball momentum and kinetic energy? Need to solve such collision problem. Metal ball of mass 1 kg moving at velocity 100 m/s hit not moving bed and hit...
  43. T

    Best paint for solar heat absorbtion?

    Hi, first-time poster. I hope this is the right area for this topic. It looks like this is the place to find smart people to give me good answers (I haven't seen any good forums dedicated to DIY solar heaters). Ok, I'm going to start building a solar air heater and I'd like to pick the best...
  44. C

    Absorbtion and Reflection of Objects, question

    I have a question which may be based in a complete misunderstanding of how "color" and our perception of it works in terms of objects absorbing certain wavelengths of light and reflecting a certain length to show that color. My question is why does an object reflect a specific wavelength...
  45. C

    Reflection and Absorbtion of Microwaves, also Masers

    I have tried searching for answers to these questions but i can't seem to find them, so if anyone could help me it would be greatly appreciated. How efficiently you can reflect microwaves? I know visible light can be reflected at 99.99% efficiency or something ridiculous like that, is it the...
  46. D

    Earths Energy & rate of absorbtion

    Homework Statement (a) Virtually all of the energy used on Earth derives originally from the Sun and solar radiation is intercepted at 1370 W m−2 at the top of the atmosphere, and that 49% of this radiation is absorbed by the Earth’s surface. Assuming that a shallow dish containing ice or...
  47. D

    Matter forms after absorbtion?

    I wonder if anyone has heard of this new (perhaps decades old?) idea I stumbled on. The matter that falls into an event horizon is quickly absorbed. Everyone knows that. But the key difference is what happens later. Underneath the energy barrier, the matter that is consummed is distributed...
  48. E

    Symmetry, absorbtion and benzene

    Hey Is it right that high symmetry molecules does not absorb light as good as low symmetry molecules? let's take an example like benzene versus benzene+hydroxyl?
  49. L

    Absorbtion and emissions - Carbon dioxide

    I hear many who believe that AGW is caused primarily by CO2 emissions in the atmosphere. I also hear from others that water vapor covers the same wave length in absorbtion. With more than 90% of the greenhouse gases being water vapor, what is the basis for the case concerning the influence of CO2.
  50. S

    Calculate Power Absorbed by Each Element in Circuit

    Homework Statement For the following circuit, determine the power absorbed by each element http://img401.imageshack.us/img401/840/pow2bl5.th.gif 2. The attempt at a solution This sign convention stuff is realllly confusing me. Can someone give me some direction here? The current...