title: NMR relaxation of the orientation of single segments in semiflexible dendrimers.
abstract: We study the orientational properties of labeled segments in semiflexible dendrimers making use of the viscoelastic approach of Dolgushev and Blumen [J. Chem. Phys. 131, 044905 (2009)]. We focus on the segmental orientational autocorrelation functions (ACFs), which are fundamental for the frequency-dependent spin-lattice relaxation times T1(ω). We show that semiflexibility leads to an increase of the contribution of large-scale motions to the ACF. This fact influences the position of the maxima of the [1/T1]-functions. Thus, going from outer to inner segments, the maxima shift to lower frequencies. Remarkably, this feature is not obtained in the classical bead-spring model of flexible dendrimers, although many experiments on dendrimers manifest such a behavior.
authors.affiliation: Faculty of Physics, St. Petersburg State University, Ulyanovskaya Str. 1, Petrodvorets, St. Petersburg, 198504 Russia.
authors.forename: Denis A
authors.initials: DA
authors.lastname: Markelov
authors.affiliation: Theoretical Polymer Physics, University of Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg, Germany.
authors.forename: Maxim
authors.initials: M
authors.lastname: Dolgushev
authors.affiliation: Faculty of Physics, St. Petersburg State University, Ulyanovskaya Str. 1, Petrodvorets, St. Petersburg, 198504 Russia.
authors.forename: Yuli Ya
authors.initials: YY
authors.lastname: Gotlib
authors.affiliation: Theoretical Polymer Physics, University of Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Blumen