Energy Levels and Visible Spectrum of Ne I

The image is in the file, NEONLINES.JPG. On the image the horizontal lines are energy levels of an excited electron in Ne I (neutral neon atom). The energies of these levels vary from 16.6 eV, the first excited state at the bottom of the image, to 21.5 eV, the dashed line at the top of the image (the energy required to ionize the neon atom). The ground state of the atom is at 0 eV, far below the bottom of the image. There are many more states not shown near the ionization energy.

Vertical lines show the allowed electron transitions that emit visible light. The color of the light emitted is indicated by the color of the line. The wavelengths range from 400 nm on the left (violet) to 750 nm on the right (red). The brightest lines in the spectrum are those in the bottom half of the image: yellow, orange, and red. This is why the light from neon looks orange.

The energy levels were obtained from C. E. Moore, Atomic Energy Levels, Vol. 1 (U.S. Gov. Printing Office, Washington, D.C., 1971).