In the often encountered case of "I" = 1/2 nuclei (e.g., 1H, 19F, 31P), the line intensities produced by a population of radicals, each possessing "M" equivalent nuclei, will follow Pascal's triangle. For example, the spectrum at the right shows that the three 1H nuclei of the CH3 radical give rise to 2"MI" + 1 = 2(3)(1/2) + 1 = 4 lines with a 1:3:3:1 ratio. The line spacing gives a hyperfine coupling constant of "a"H = 23 "G" for each of the three 1H nuclei. Note again that the lines in this spectrum are "first derivatives" of absorptions.