Optical oscillator strength distribution of amino acids from 3 to 250 eV and examination of the Thomas–Reiche–Kuhn sum rule

Abstract Absorption spectra of thin films of glycine (Gly), alanine (Ala), valine (Val), serine (Ser), leucine (Leu), phenylalanine (Phe) and methinine (Met) were measured in absolute values of absorption cross section σ( E ) for the photon energy E from 3 to 250 eV. We translated σ( E ) into the optical oscillator strength distribution df/dE and we examined the Thomas–Reiche–Kuhn sum rule [Hirschfelder, J.O., Curtiss, C.F., Bird, R.B., 1954. Molecular Theory of Gases and Liquids. Wiley, New York, p. 890]. We concluded that T–R–K sum rule was correctly applicable for such relatively large size of biomolecules.