title: Ultrafast vibrational spectroscopy of a degenerate mode of guanidinium chloride.
abstract: Nearly degenerate asymmetric stretches with perpendicular transition dipole moments of the deuterated guanidinium cation (DGdm(+)) in D(2)O and D-glycerol/D(2)O mixtures at 1600 cm(-1) were investigated by linear FTIR spectroscopy and polarization dependent femtosecond pump-probe spectroscopy. The vibrational coupling of the asymmetric stretches of guanidinium occurs within 0.5 ps and leads to fast decay of the anisotropy to a level of 0.1. A systematic study of the influence of the coherence transfer on pump-probe signals is given. Following this decay, the anisotropy decays with a time constant of 4.1 ps in D(2)O by rotational diffusion about an axis perpendicular to the DGdm(+) mean plane. The presence of aggregation was demonstrated for concentrations higher than 0.2 M.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Dmitriy Yu
authors.initials: DY
authors.lastname: Vorobyev
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Kuo
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Chen
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Kuroda
authors.forename: J Nathan
authors.initials: JN
authors.lastname: Scott
authors.forename: Jane M
authors.initials: JM
authors.lastname: Vanderkooi
authors.forename: Robin M
authors.initials: RM
authors.lastname: Hochstrasser
mesh_terms: D016880:Anisotropy; D003198:Computer Simulation; D017666:Deuterium Oxide / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D019791:Guanidine / Q000737:chemistry*; D008958:Models, Molecular; D017550:Spectroscopy, Fourier Transform Infrared; D014732:Vibration
chemical_list: D017666:Deuterium Oxide; D019791:Guanidine; D005990:Glycerol