where S = 2.9352 × 1060 C−2 mol−1. Fig. 2 shows the spectra of caffeine in water given as a function of molar decadic absorption coefficient over wave number versus wave number (View the MathML source versus View the MathML source). The integrated area under this curve 105.92 m2 mol−1 was obtained by integrating from View the MathML source to View the MathML source therefore, the transitional dipole moment of caffeine in water μfi = 10.40 × 10−30 C m was obtained.