Unlike many laser systems, transitions in the CO₂ gas laser occur not only between electronic energy levels, but also between rotational and vibrational energy levels.  As a molecule in a gaseous state, CO₂ is free to both vibrate and rotate.  A complete energy understanding of the energy levels of CO₂, then, must take these into account. Transitions between the rotational levels within particular vibrational modes results in the emission of photons with wavelengths in the infrared region.  Specifically, CO₂ emits photons at 10.6um and 9.6um.  The mechanism for this emission is discussed below, as well as different properties of the CO₂ molecule regarding its vibration, rotation, and structure.  

Abstract:

             In our study of the molecular properties of CO₂, we determined the temperature in the laser tube by a study of the power of the laser as a function of the position of the diffraction grating.  From this data alone, we were also capable of calculating the moment of inertia of a CO₂molecule, as well as the separation or bond length of the carbon and oxygen.  We also did an experiment using an acoustic chamber.  Again, we recorded the power output of the laser as a function of grating position.  Once this output read from the acoustic chamber was normalized with the output from the laser tube, we were able to determine the temperature of the CO₂in the chamber.  This data was also used to analyze the population density.  Our experiment required editing a LabView VI (virtual instrument) to record two sets of simultaneous data.