title: Terahertz time-domain spectroscopy of amino acids and polypeptides.
abstract: Frequency-dependent absorption coefficients and refractive indices of amino acids (glycine and l-alanine) and polypeptides (polyglycine and poly-l-alanine) in the wavenumber region from 7 to 55 cm(-1) were measured by terahertz time-domain spectroscopy. A vibrational band was observed at 45.5 cm(-1) for polyglycine, which was assigned as an interchain mode. The reduced absorption cross sections of the amino acids and polypeptides show power-law behavior. The exponents are different between the monomers and polymers, and those of the two polypeptides suggest that the time dependences of the total dipole moments are similar in the timescale of subpico- to picoseconds.
authors.affiliation: Molecular Photoscience Research Center, and Graduate School of Science and Technology, Kobe University, Nada, Kobe 657-8501, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tominaga
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sasakawa
authors.forename: Atsuo
authors.initials: A
authors.lastname: Tamura
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Murakami
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ohtake
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sarukura
mesh_terms: D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D001703:Biophysics / Q000379:methods; D005998:Glycine / Q000737:chemistry; D015233:Models, Statistical; D010455:Peptides / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods*; D013055:Spectrophotometry, Infrared; D013696:Temperature; D013997:Time Factors
chemical_list: D000596:Amino Acids; D010455:Peptides; D011108:Polymers; C019529:polyalanine; C011080:polyglycine; D000409:Alanine; D005998:Glycine