OBSERVATION OF THE LOWEST A(G) EXCITED-STATE LYING IN THE OPTICAL GAPIN POLYDIACETYLENE BY MEANS OF 2ND-HARMONIC GENERATION SPECTROSCOPY

Citation
T. Manaka et al., OBSERVATION OF THE LOWEST A(G) EXCITED-STATE LYING IN THE OPTICAL GAPIN POLYDIACETYLENE BY MEANS OF 2ND-HARMONIC GENERATION SPECTROSCOPY, Synthetic metals, 95(2), 1998, pp. 155-158
Citations number
22
Categorie Soggetti
Physics, Condensed Matter","Material Science","Polymer Sciences
Journal title
ISSN journal
03796779
Volume
95
Issue
2
Year of publication
1998
Pages
155 - 158
Database
ISI
SICI code
0379-6779(1998)95:2<155:OOTLAE>2.0.ZU;2-I
Abstract
We have observed second-harmonic generation (SHG) spectra in polydiace tylene (poly [5,7-dodecadiyne-1,12-diyl-bis-ethylurethane], PDA-4U2 fo r short) films of red and blue forms. In addition to resonant peaks lo cated at the high-energy side of the main absorption peak, a new reson ant peak was observed at the lower-energy side of the absorption peak in blue-form PDA-4U2. In contrast, in red-form PDA-4U2, the SHG resona nce peak position in the lower-energy side coincides with the absorpti on peak position. The resonance enhancement of SHG originates from the electric-quadrupole transition to the dipole-forbidden state. The low est resonance peak observed in the blue-form PDA-4U2 strongly suggests the existence of the lowest A(g), excited state lying below the lowes t B-u, excited state. (C) 1998 Elsevier Science S.A. All rights reserv ed.