An experiment is performed on a sample of atoms known to have a ground state of —5.0 eV. The gas is illuminated with "white light" (400 - 700 nm). A spectrometer capable of analyzing radiation in this range is used to measure the radiation. The sample is observed to absorb light at only 400 nm. After the "white light" is turned off, the sample is observed to emit visible radiation of 400 nm and 600 nm.

 

1. the ground state
2. the energy level to which the system was first excited
3. one other energy level that the experiment suggests may exist