Lorenz, Ulrich J.Rizzo, Thomas R.2012-06-262012-06-262012-06-26201210.1021/ja3023708https://infoscience.epfl.ch/handle/20.500.14299/82399WOS:000306297600001Our investigation of the phenylalanine/serine (Phe/Ser) protonated dimer suggests that the intermolecular interaction between the two amino acids is more complex than could have been anticipated from previous studies of similar systems. Isomer-specific infrared (IR) spectra, rec-orded at an internal temperature of ~10 K, demonstrate the presence of at least five isomers with non-zwitterionic structures. Moreover, isotopic substitution experiments provide evidence for different protonation sites among the-se isomers.cold-ion spectroscopymass spectrometryion trapsamino acid dimerstext::journal::journal article::research article