1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Questions about light absorption

  1. Nov 30, 2011 #1
  2. jcsd
  3. Dec 1, 2011 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    It is to do with how absorption happens.

    Let's see if I can give you a simple model:

    A photon encounters an atom, it is absorbed if the energy of the photon matches closely enough with the difference in energy between two atomic energy levels. The atom becomes excited for a while, then releases the energy in a series of lower energy jumps or mechanically by jostling adjacent atoms ... so the material heats up.

    The higher the energy of the photon, the bigger the energy hit, and for very high energy (eg x-rays or gamma rays) the energy is enough to ionize the atom. Thus even x-rays do not go through everything. In fact, x-ray absorbtion spectroscopy is an important tool.

    For a wider discussion see:
  4. Dec 1, 2011 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    There is a difference between absorption by atomic gasses, versus absorption by a solid. Please read the FAQ subforum in the General Physics forum, especially the discussion on "phonons".

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook