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

How are emission spectra of gases affected by being in water?

  1. Jan 1, 2010 #1
    Happy New Year to all you Physics Geniuses out there!

    I have a question concerning how the optical emission spectrum of a gas would be affected by being dissolved in water. I know very little about spectroscopy so please forgive me if this seems like an idiotic question.

    Let's assume I have a gas like neon, which has a very precise emission spectrum when it's excited in the gaseous state. What happens to its emission spectrum if those neon atoms are now dissolved in water and something excites the neon, for example a strong chemical reaction? Would the spectrum emitted by the excited "aqueous" neon look anything like the spectrum seen in its gaseous state? If not, is there some way to predict what that spectrum might be or does the character of emission get insanely complex once an atom is surrounded by so many other molecules, etc.?

    I know neon doesn't dissolve very well in water, but I'm just using that as a hypothetical example.

    many thanks for your time,
  2. jcsd
  3. Jan 3, 2010 #2
    One thing to keep in mind is that the water will bend and refract the light. Good ol' Snell's Law.
  4. Jan 8, 2010 #3

    thanks for that reminder. But I am mostly interested in how an emission line of a normally gaseous substance might change after it is dissolved in water. For example, if neon gives an emission line at XYZ nanometers, will that emission line be shifted if the neon is dissolved in an aqueous solution wherein it gets excited by, say, a laser pulse, electric charge or high energy chemical reaction, etc.?

  5. Jan 10, 2010 #4

    Claude Bile

    User Avatar
    Science Advisor

    Good question. Some effects worth keeping in mind;

    - Stark splitting due to an applied E-field. Especially if the water is not de-ionised.
    - Chemical changes, for example, carbon dioxide will form carbonic acid upon being dissolved in water.

    There are no doubt other effects.

    Might I suggest too, looking up the nearly analogous case of emitters embedded in solid media. For example, how gaseous Cu compare to Cu ions embedded in a crystal matrix. This may also provide some useful insights.

    Best of luck,
  6. Jan 10, 2010 #5
    Hi Claude,

    Thanks for the suggestions. Based on what I've just read about the Stark Effect, I guess one would expect a lot of shifting around and splitting up of the emission lines, especially if the aqueous solution is full of complex chemicals. From that, I am therefore guessing it is not possible to simply derive how such an emission line would be shifted, even if we were dealing with an inert gas like neon, helium, etc. which does not dissolve very well in water.

    much obliged for your help,
  7. Jan 10, 2010 #6

    oh, but on the other hand, I suppose it would not be totally impossible to perhaps dissolve a known inert gas in an aqueous solution and run some experiments, read the emission spectra, then use those resulting emission lines later on as some kind of indicator. I suppose that approach might still be possible.

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