Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Lasers affecting water

  1. Dec 1, 2006 #1
    Is there a way to make a laser affect water and what would it do to it?

    I am trying to figure out a way to aggitate the hydogen and oxygen molecules in water to make them want to break apart. Would a laser make a difference? Any other suggestions. Thank you all for your help in advance.
  2. jcsd
  3. Dec 1, 2006 #2


    User Avatar

    Staff: Mentor

    What wavelengths of light are absorbed by water? What lasers generate those wavelengths?
  4. Dec 1, 2006 #3
    Well, if you use a photon energy higher than the binding energy of water molecules, you'll cause the component atoms to dissociate temporarily. However, the problem with that is that water molecules have the lowest energy of the hydrogen-oxygen compounds, which means that the dissociated atoms will probably recombine to form water molecules, and not a mixture of hydrogen and oxygen molecules. Presumably, if you could determine the difference between the energies of the water state and the hydrogen-oxygen mixture state, a photon at that energy would do the trick. However, this begs the question: what's wrong with just using electrolysis?
  5. Dec 1, 2006 #4


    User Avatar
    Gold Member

    isn't electrolysis really inefficient

    but then again, how efficiant would using lasers be v.s. electrolysis?
    or is that irellavent to the purpose of your question/experiment?
    "that which does not kill me, postpones the inevidible" despair.com
  6. Dec 2, 2006 #5


    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    Hey microwaves, as in A microwave in your kitchen, sure affect water; they heat it up. So I suppose you could build a maser (microwave laser) to boil water from a distance. Take THAT! Aquaman!
  7. Dec 2, 2006 #6


    User Avatar
    Gold Member

    do they have "masers" in the world?
    if not, it sounds like a pretty prophitable idea to me.......
    they managed to do it with light and sound.
  8. Dec 2, 2006 #7
    Electrolysis isn't efficient, but neither are most laser systems. And to answer your question about masers, masers were actually around before lasers! In fact, if you look at some of the earlier literature about lasers, you'll find that they're referred to as "optical masers." :biggrin:
  9. Dec 2, 2006 #8
    i beleive taking a glass of water and puting a 2 wires into it, each wire hooked into each charge of an alkaline battery, seperates the water, but i'm not sure.

    Lasers may work but it depends on the type of laser (and/or maser) ;]
  10. Dec 4, 2006 #9
    From wikipedia:

    Now then, what type of laser emits infrared? Think CO2..

    I don't think a laser, however, will do what you need. It will simply heat up the water. Of course, this will encourage the seperation of molecules to some extent. (maybe use hot water and then do electroylsis the conventional way would work just as well).

    The reason a microwave heats water is because water is a dipole molecule - it has a slightly postive and negative charge on each end, and it will line itself up with a powerful electric field. But a laser will not really help in that area - remember, you are shooting photons at it, which the electrons will absorb and raise to higher energy states (I think I stated that correctly).

    A laser could also vaporize water - however, water can absorb a tremendous amount of energy before vaporization.

    Last edited: Dec 4, 2006
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?