title: Femtosecond study of self-trapped vibrational excitons in crystalline acetanilide.
abstract: Femtosecond IR spectroscopy of delocalized NH excitations of crystalline acetanilide confirms that self-trapping in hydrogen-bonded peptide units exists and does stabilize the excitation. Two phonons with frequencies of 48 and 76 cm (-1) are identified as the major degrees of freedom that mediate self-trapping. After selective excitation of the free exciton, self-trapping occurs within a few 100 fs. Excitation of the self-trapped states disappears from the spectral window of this investigation on a 1 ps time scale, followed by a slow ground state recovery of the hot ground state within 18 ps.
authors.affiliation: Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Bornstrasse 2a, 12489 Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Edler
authors.forename: P
authors.initials: P
authors.lastname: Hamm
authors.forename: A C
authors.initials: AC
authors.lastname: Scott
mesh_terms: D000083:Acetanilides / Q000737:chemistry*; D003460:Crystallization; D006860:Hydrogen Bonding; D018716:Molecular Mimicry; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D000083:Acetanilides; D010455:Peptides