This artist's interpretation intends to show small grains of a reference material disappearing or floating away. Also shown are two lasers, red and blue, which represent the two different colored lasers used by our instrument. Also visible are linear molecules of carbon dioxide (collections of three balls), CO2.
A recent blog from previous JILA postdoc Adam J. Fleisher discusses his current work at NIST, focusing on developing artifact-free, SI-traceable measurements of carbon dioxide in the air. You can read the full blog here.