title: Quantum Mechanical Calculations of Vibrational Sum-Frequency-Generation (SFG) Spectra of Cellulose: Dependence of the CH and OH Peak Intensity on the Polarity of Cellulose Chains within the SFG Coherence Domain.
abstract: Vibrational sum-frequency-generation (SFG) spectroscopy is capable of selectively detecting crystalline biopolymers interspersed in amorphous polymer matrices. However, the spectral interpretation is difficult due to the lack of knowledge on how spatial arrangements of crystalline segments influence SFG spectra features. Here we report time-dependent density functional theory (TD-DFT) calculations of cellulose crystallites in intimate contact with two different polarities: parallel versus antiparallel. TD-DFT calculations reveal that the CH/OH intensity ratio is very sensitive to the polarity of the crystallite packing. Theoretical calculations of hyperpolarizability tensors (βabc) clearly show the dependence of SFG intensities on the polarity of crystallite packing within the SFG coherence length, which provides the basis for interpretation of the empirically observed SFG features of native cellulose in biological systems.
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, and ‡Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16802, United States.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Lee
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, and ‡Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16802, United States.
authors.forename: Xing
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, and ‡Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16802, United States.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Weiss
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, and ‡Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16802, United States.
authors.forename: Lasse
authors.initials: L
authors.lastname: Jensen
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, and ‡Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16802, United States.
authors.forename: Seong H
authors.identifier: http://orcid.org/0000-0002-8575-7269
authors.initials: SH
authors.lastname: Kim
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis / Q000379:methods; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D014732:Vibration
chemical_list: D011108:Polymers; D002482:Cellulose