Photofragment ionization-loss stimulated Raman spectroscopy of a hydrated neurotransmitter: 2-phenylethylamine-water

Different types of spectral signatures and their interpretation provide valuable information on intra- and inter-molecular interactions that lead to unique shapes of molecules and clusters. Here, ionization-loss stimulated Raman (ILSR) spectra of the 2-phenylethylamine-water (PEA-H₂O) cluster were obtained by monitoring the spectral signatures of PEA and of CH₂NH₂-H₂O (a hydrated portion of the PEA tail) fragment ions. The ILSR spectra of both fragments were found to be similar, indicating that they are actually reminiscent of the PEA-H₂O cluster signature. Comparison of the photofragment spectra to anharmonic calculated Raman spectra of the different conformers of the PEA-H₂O clusters, suggests a structure with PEA similar to that of the most stable gauche conformer, with H₂O hydrogen bonded to the nitrogen lone pair.