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Intrinsic and extrinsic — Linear and nonlinear optical excitations in conjugated polymers
Synthetic Metals, 41-43 (1991) 1205
INTRINSIC
AND EXTRINSIC
-
1205
LINEAR
AND
NONLINEAR
OPTICAL EXCITATIONS IN CONJUGATED POLYNERS G.Leising, F . S t e l z e r and K . B i e b e r n i k Technische UniversitAt Graz, Petersgasse 16,A-8010 Graz; Austria P . K n o l l and K . F i e d l e r I n s t i t u t f . Experimentalphysik, U n i v e r s i t a t Graz U n i v e r s i t ~ t s p l a t z 5, A-8010 Graz; Austria
The m o s t important question in the discussion o f the electronic excitations o f conjugated polymers is a distinction between i n t r i n s i c optical properties and e x t r i n s i c o n e s (defects, morphology, disorder, e t c . ) . C o n t r i b u t i n g to t h i s prob]em we present r e s u l t s o f o p t i c a l i n v e s t i g a t i o n s on d i f f e r e n t types and morphological forms o f conjugated polymers. The influence o f the morphology on the bandshape of the interband t r a n s i t i o n o f polyacetylene has been studied on soluble-graft-polyacetylene, Shirakawa-polyacetylene, disordered polyacetylene (Durham-type), highly oriented nonfibrous crystalline polyacetylene (Durham-Graz-type), polyacetylene-polynorbornene triblock c o p o l y m e r s ( d i s o r d e r e d and oriented) and o r i e n t e d p o l y a c e t y l e n e s e q u e n c e s i n a PVCmatrix. The nature o f e l e c t r o n i c or v i b r o n i c states in the band-edge region is discussed in the framework of these results. The d o p i n g i n d u c e d n e a r midgap a b s o r p t i o n seems t o reflect the density of states in the interband transition region for the d i f f e r e n t systems. A d d i t i o n a l l y , we present o p t i c a l studies on pure and doped polyparaphenylene and p o l y ( v i n y l e n s cyclopentadiene-l,4ylene/furan-2,5-ylene), b o t h p r e p a r e d by p r e c u r s o r r o u t e s . The n o n l i n e a r o p t i c a l behavior of these conjugated polymers and c o p o l y m e r s a r e compared by means o f triple frequency g e n e r a t i o n and f r e q u e n c y m i x i n g . The measurements were done w i t h an i n j e c t i o n seeded Nd-YAG l a s e r u s i n g t h e fundamental frequency as w e l l as t h e d o u b l e d and Dye l a s e r shifted frequencies.
Elsevier Sequoia/Printed in The Netherlands
INTRINSIC
AND EXTRINSIC
-
1205
LINEAR
AND
NONLINEAR
OPTICAL EXCITATIONS IN CONJUGATED POLYNERS G.Leising, F . S t e l z e r and K . B i e b e r n i k Technische UniversitAt Graz, Petersgasse 16,A-8010 Graz; Austria P . K n o l l and K . F i e d l e r I n s t i t u t f . Experimentalphysik, U n i v e r s i t a t Graz U n i v e r s i t ~ t s p l a t z 5, A-8010 Graz; Austria
The m o s t important question in the discussion o f the electronic excitations o f conjugated polymers is a distinction between i n t r i n s i c optical properties and e x t r i n s i c o n e s (defects, morphology, disorder, e t c . ) . C o n t r i b u t i n g to t h i s prob]em we present r e s u l t s o f o p t i c a l i n v e s t i g a t i o n s on d i f f e r e n t types and morphological forms o f conjugated polymers. The influence o f the morphology on the bandshape of the interband t r a n s i t i o n o f polyacetylene has been studied on soluble-graft-polyacetylene, Shirakawa-polyacetylene, disordered polyacetylene (Durham-type), highly oriented nonfibrous crystalline polyacetylene (Durham-Graz-type), polyacetylene-polynorbornene triblock c o p o l y m e r s ( d i s o r d e r e d and oriented) and o r i e n t e d p o l y a c e t y l e n e s e q u e n c e s i n a PVCmatrix. The nature o f e l e c t r o n i c or v i b r o n i c states in the band-edge region is discussed in the framework of these results. The d o p i n g i n d u c e d n e a r midgap a b s o r p t i o n seems t o reflect the density of states in the interband transition region for the d i f f e r e n t systems. A d d i t i o n a l l y , we present o p t i c a l studies on pure and doped polyparaphenylene and p o l y ( v i n y l e n s cyclopentadiene-l,4ylene/furan-2,5-ylene), b o t h p r e p a r e d by p r e c u r s o r r o u t e s . The n o n l i n e a r o p t i c a l behavior of these conjugated polymers and c o p o l y m e r s a r e compared by means o f triple frequency g e n e r a t i o n and f r e q u e n c y m i x i n g . The measurements were done w i t h an i n j e c t i o n seeded Nd-YAG l a s e r u s i n g t h e fundamental frequency as w e l l as t h e d o u b l e d and Dye l a s e r shifted frequencies.
Elsevier Sequoia/Printed in The Netherlands