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!

Molecular Vibration and Translational Kinetic Energy in a Gas

  1. Nov 30, 2009 #1
    Mods, I hope I'm not breaching any guidelines here, haven't had any responses in General Physicsand thought perhaps the question might be more at home here.

    I understand that CO2 molecules absorb infrared at 2.7, 4.3 and 15 microns, this makes them become vibrationally excited (rocking, stretching, bending, I don't know all the modes).

    I have a few questions from this point:

    1. When the CO2 molecule re-emits that energy is it obliged to do so at wavelengths similar to its absorption spectrum; I had assumed so but I don't know for certain that this is the case despite googling the hell out of it. CO2 does not behave in anyway like a blackbody when it re-radiates, correct?

    2. In a gas, can the vibrational energy be passed from the CO2 molecule to other molecules during collisions, or can it only pass on as radiation? I understand there's a lattice effect in solids, but I don't think its relevant in a gas. Can molecular vibration 'turn into' translational kinetic energy?

    3. Assuming that the CO2 molecule re-radiates at 2.7, 4.3 and 15 microns, I imagine that H20 may 'feel' that radiation at 4.3 microns, but I guess what I'm really asking is, can vibrationally excited CO2 molecules, do work on the rest of the molecules in the gas? Or is the vibrational energy of a CO2 molecule limited to doing work on other CO2 molecules?

    P.S the gas is not an ideal gas, it's air.
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted