Notices
Results 1 to 15 of 15
Like Tree2Likes
  • 1 Post By molecool
  • 1 Post By exchemist

Thread: Light-matter interaction

  1. #1 Light-matter interaction 
    Forum Sophomore
    Join Date
    Feb 2014
    Posts
    115
    Why do they call it a light-matter interaction when the photoelectric effect only applies to metals and not all kinds of matter? Not to mention Thomson/Compton Scattering and Pair Production.


    dan hunter likes this.
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Ph.D.
    Join Date
    Mar 2014
    Posts
    940
    Could it be that 'light-matter interaction' is a broad category of experimentation/observation and the photoelectric effect is a subset of this category? When I did a search for 'light-matter interaction' I got many hits for articles where the photoelectric effect was not discussed. (I am not pretending to understand these various articles.)


    Reply With Quote  
     

  4. #3  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    3,403
    Quote Originally Posted by molecool View Post
    Why do they call it a light-matter interaction when the photoelectric effect only applies to metals and not all kinds of matter? Not to mention Thomson/Compton Scattering and Pair Production.
    Well, it is one type of light-matter interaction, isn't it?
    Reply With Quote  
     

  5. #4  
    Forum Professor
    Join Date
    Jul 2008
    Location
    New York State
    Posts
    1,088
    Photoelectric effect for gamma rays occurs with all elements.
    Reply With Quote  
     

  6. #5  
    Forum Sophomore
    Join Date
    Feb 2014
    Posts
    115
    Quote Originally Posted by Chucknorium View Post
    Could it be that 'light-matter interaction' is a broad category of experimentation/observation and the photoelectric effect is a subset of this category? When I did a search for 'light-matter interaction' I got many hits for articles where the photoelectric effect was not discussed. (I am not pretending to understand these various articles.)
    Attenuation - Wikipedia, the free encyclopedia
    The primary causes of attenuation in matter are the photoelectric effect, compton scattering, and, for photon energies of above 1.022 MeV, pair production.
    Primary causes?
    Reply With Quote  
     

  7. #6  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    3,403
    Quote Originally Posted by mathman View Post
    Photoelectric effect for gamma rays occurs with all elements.
    Can you explain that a bit? As far as I recall, the photoelectric effect is excitation of bonding (outer shell) electrons from the surface of a metal, whereas gamma rays are of such an energy that they interact with atomic nuclei.
    Reply With Quote  
     

  8. #7  
    Forum Sophomore
    Join Date
    Feb 2014
    Posts
    115
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by molecool View Post
    Why do they call it a light-matter interaction when the photoelectric effect only applies to metals and not all kinds of matter? Not to mention Thomson/Compton Scattering and Pair Production.
    Well, it is one type of light-matter interaction, isn't it?
    But it states here Attenuation - Wikipedia, the free encyclopedia (in the electromagnetic section of the article) that
    The primary causes of attenuation in matter are the photoelectric effect, compton scattering, and, for photon energies of above 1.022 MeV, pair production.
    What do they mean "primary causes"??
    Reply With Quote  
     

  9. #8  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    5,394
    I read that to mean the "most important" causes. There may be other things going on but the named effects are the main cause of attenuation in matter.
    Reply With Quote  
     

  10. #9  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    3,403
    Quote Originally Posted by molecool View Post
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by molecool View Post
    Why do they call it a light-matter interaction when the photoelectric effect only applies to metals and not all kinds of matter? Not to mention Thomson/Compton Scattering and Pair Production.
    Well, it is one type of light-matter interaction, isn't it?
    But it states here Attenuation - Wikipedia, the free encyclopedia (in the electromagnetic section of the article) that
    The primary causes of attenuation in matter are the photoelectric effect, compton scattering, and, for photon energies of above 1.022 MeV, pair production.
    What do they mean "primary causes"??
    It looks to me as if you are reading it back to front. Surely they are simply saying that among the various causes of attenuation of light in matter, the photoelectric effect is one of the main (primary) ones.
    Reply With Quote  
     

  11. #10  
    Forum Professor
    Join Date
    Jul 2008
    Location
    New York State
    Posts
    1,088
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by mathman View Post
    Photoelectric effect for gamma rays occurs with all elements.
    Can you explain that a bit? As far as I recall, the photoelectric effect is excitation of bonding (outer shell) electrons from the surface of a metal, whereas gamma rays are of such an energy that they interact with atomic nuclei.
    gamma rays interact with matter primarily in three ways, Compton scattering (electrons), phtoelectric effect (electrons), and pair production (in the presence of nuclei - gamma ray energy > 1.022 Mev).
    Reply With Quote  
     

  12. #11  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    3,403
    Quote Originally Posted by mathman View Post
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by mathman View Post
    Photoelectric effect for gamma rays occurs with all elements.
    Can you explain that a bit? As far as I recall, the photoelectric effect is excitation of bonding (outer shell) electrons from the surface of a metal, whereas gamma rays are of such an energy that they interact with atomic nuclei.
    gamma rays interact with matter primarily in three ways, Compton scattering (electrons), phtoelectric effect (electrons), and pair production (in the presence of nuclei - gamma ray energy > 1.022 Mev).
    This is just repeating the assertion. I still do not understand how a gamma ray can participate in the photoelectric effect.

    Perhaps another reader can clarify for me.
    Reply With Quote  
     

  13. #12  
    Forum Sophomore
    Join Date
    Feb 2014
    Posts
    115
    Quote Originally Posted by PhDemon View Post
    I read that to mean the "most important" causes. There may be other things going on but the named effects are the main cause of attenuation in matter.
    But what about decrease in intensity of light through a translucent object?
    Reply With Quote  
     

  14. #13  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    3,403
    Quote Originally Posted by molecool View Post
    Quote Originally Posted by PhDemon View Post
    I read that to mean the "most important" causes. There may be other things going on but the named effects are the main cause of attenuation in matter.
    But what about decrease in intensity of light through a translucent object?
    A translucent object, being cloudy in appearance, scatters light. The proportion transmitted in the original direction of the incident beam is reduced, with the balance being radiated off in random directions.
    Reply With Quote  
     

  15. #14  
    Forum Sophomore
    Join Date
    Feb 2014
    Posts
    115
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by molecool View Post
    Quote Originally Posted by PhDemon View Post
    I read that to mean the "most important" causes. There may be other things going on but the named effects are the main cause of attenuation in matter.
    But what about decrease in intensity of light through a translucent object?
    A translucent object, being cloudy in appearance, scatters light. The proportion transmitted in the original direction of the incident beam is reduced, with the balance being radiated off in random directions.
    But it does not apply any of the so-called light-matter interactions mentioned here, or does it?
    Reply With Quote  
     

  16. #15  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    3,403
    Quote Originally Posted by molecool View Post
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by molecool View Post
    Quote Originally Posted by PhDemon View Post
    I read that to mean the "most important" causes. There may be other things going on but the named effects are the main cause of attenuation in matter.
    But what about decrease in intensity of light through a translucent object?
    A translucent object, being cloudy in appearance, scatters light. The proportion transmitted in the original direction of the incident beam is reduced, with the balance being radiated off in random directions.
    But it does not apply any of the so-called light-matter interactions mentioned here, or does it?
    Well simple scattering does not attenuate the light, it just redirects it. The total light energy leaving the object is the same as the total amount entering the object. It has just been split up and sent bouncing off in all directions. Whereas the attenuation processes you listed originally involve loss of energy of the light, to other forms of energy in the matter it is interacting with.
    molecool likes this.
    Reply With Quote  
     

Similar Threads

  1. Spiral light paths and dark matter
    By Laurieag in forum Personal Theories & Alternative Ideas
    Replies: 0
    Last Post: April 29th, 2014, 07:10 PM
  2. Is light considered matter?
    By Thrillseeker in forum Physics
    Replies: 40
    Last Post: January 9th, 2014, 07:41 AM
  3. Light = Dark Matter ???
    By Tazmainian Guru in forum Personal Theories & Alternative Ideas
    Replies: 4
    Last Post: September 28th, 2011, 06:16 PM
  4. speed of light through anti matter
    By Lucas D in forum Physics
    Replies: 2
    Last Post: June 14th, 2010, 04:07 AM
  5. New concept for gravity/light interaction
    By arKane in forum Personal Theories & Alternative Ideas
    Replies: 12
    Last Post: November 19th, 2009, 02:08 PM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •