Question

Go to www.nist.gov/pml/data/asd.cfm, click on Levels, enter C I in Spectrum, and click Retrieve Data to find the energy levels of the 2s22p3s configuration of C. Then use the selection rules given in Prob. 11.31 to find the wavenumbers and wavelengths of all allowed transitions between the levels of 2s22p3s and the levels of 2s22p2 given in Prob. 11.31. Check your wavelengths by clicking on Lines instead of Levels.
In Problem 11.31
For the carbon atom, the levels that arise from the 1s22s22p2 configuration are

And the energy levels of the 1s22s2p= configuration are

Answer 1

The 2s22p3s levels are listed as:

 

 

The discussion at the beginning of Prob. 11.31 gives the following allowed transition wavenumbers in cm−1 (the first number listed for each transition) and wavelengths in nm (the second number listed), where the first level in each pair arises from the 2s22p3s configuration:

 

The calculated wavelengths agree with the ones listed in the NIST database except for the wavelength of the last line, which NIST gives as 247.856 nm. 

This is because NIST lists wavelengths that are between 200 nm and 2000 nm as wavelengths in air (rather than in vacuum), so the index of refraction of air affects the NIST value.