Even Parity States in Ppv, Polythiophene and Polysilanes

1993 ◽  
Vol 328 ◽  
Author(s):  
F. Guo ◽  
M. Chandross ◽  
S. Mazumdar
Keyword(s):  
Conjugated Polymers ◽  
Parity State ◽  
Photoinduced Absorption ◽  
Absorption Data ◽  
Two Photon ◽  
Bond Alternation ◽  
Theoretical Evidence ◽  
Long Chains

ABSTRACTTwo photon absorptions (TPA) in conjugated polymers with large bond alternation are reinterpreted. TPA to the 2Ag in long chains should be tiny due to cancellation effects, and therefore the observed strong, narrow TPA is to a higher even parity state. We also present the first theoretical evidence for bound biexcitons, and explain recent photoinduced absorption data.

scholarly journals Investigating Pulse Morphology in GX 1+4

1998 ◽  
Vol 15 (2) ◽  
pp. 217-221 ◽  
Author(s):  
Michelle C. Storey ◽  
J. G. Greenhill ◽  
T. Kotani
Keyword(s):  
Pulse Shape ◽  
Transition Probabilities ◽  
Low Frequency ◽  
Opening Angle ◽  
Emission Model ◽  
Two Photon ◽  
Maximum Value ◽  
Emission Transition ◽  
Cyclotron Emission ◽  
Theoretical Evidence

AbstractObservational and theoretical evidence points to the existence of an unusually high magnetic field on GX 1+4. The pulsar is thus an ideal laboratory for studying two-photon cyclotron emission, an important source of photons of frequency significantly less than the cyclotron frequency in X-ray pulsars. Low-frequency approximations to the two-photon cyclotron emission transition probabilities are derived. These are used to calculate the theoretical opening angle of the double-humped pulse shape predicted by the two-photon cyclotron emission model. The theoretical pulse shape, incorporating the effects of gravitational light bending, is compared with observations of GX 1+4. Observed light curves have opening angles consistent with the theoretically predicted maximum value.

Two-Photon Spectroscopy of π-Conjugated Polymers:  The Case of Poly[1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne] (PolyDCHD-HS)

2001 ◽  
Vol 105 (32) ◽  
pp. 7759-7764 ◽  
Author(s):  
Laura Moroni ◽  
Pier Remigio Salvi ◽  
Cristina Gellini ◽  
Giovanna Dellepiane ◽  
Davide Comoretto ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Two Photon

scholarly journals Nonlinear Optical Pigments. Two-Photon Absorption in Crosslinked Conjugated Polymers and Prospects for Remote Nonlinear Optical Thermometry

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1670
Author(s):  
Jan K. Zaręba ◽  
Marcin Nyk ◽  
Marek Samoć
Keyword(s):  
Solid State ◽  
Conjugated Polymers ◽  
Nonlinear Optical ◽  
Photon Absorption ◽  
Model Compounds ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Sensing Applications ◽  
Spectrally Resolved ◽  
The Impact

Nonlinear optical (NLO) pigments are compounds insoluble in solvents that exhibit phenomena related to nonlinear optical susceptibilities (χ(n) where n = 2,3,...), e.g., two-photon absorption (2PA) which is related to the imaginary part of χ(3). Determination of spectrally-resolved 2PA properties for NLO pigments of macromolecular nature, such as coordination polymers or crosslinked polymers, has long been a challenging issue due to their particulate form, precluding characterizations with standard techniques such as Z-scan. In this contribution, we investigate thus far unknown spectrally-resolved 2PA properties of a new subclass of NLO pigments—crosslinked conjugated polymers. The studied compounds are built up from electron-donating (triphenylamine) and electron-withdrawing (2,2’-bipyridine) structural fragments joined by vinylene (Pol1) or vinyl(4-ethynylphenyl) (Pol2) aromatic bridges. 2PA properties of these polymers have been characterized in broad spectral range by specially modified two-photon excited fluorescence (TPEF) techniques: solid state TPEF (SSTPEF) and internal standard TPEF (ISTPEF). The impact of self-aggregation of aromatic backbones on the 2PA properties of the polymers has been evaluated through extended comparisons of NLO parameters, i.e., 2PA cross sections (σ2) and molar-mass normalized 2PA merit factors (σ2/M) with those of small-molecular model compounds: Mod1 and Mod2. By doing this, we found that the 2PA response of Pol1 and Pol2 is improved 2–3 times versus respective model compounds in the solid state form. Further comparisons with 2PA results collected for diluted solutions of Mod1 and Mod2 supports the notion that self-aggregated structure contributes to the observed enhancement of 2PA response. On the other hand, it is clear that Pol1 and Pol2 suffer from aggregation-caused quenching phenomenon, well reflected in time-resolved fluorescence properties as well as in relatively low values of quantum yield of fluorescence. Accordingly, despite improved intrinsic 2PA response, the effective intensity of two-photon excited emission for Pol1 and Pol2 is slightly lower relative to Mod1 and Mod2. Finally, we explore temperature-resolved luminescence properties under one- (377 nm), two- (820 nm), and three-photon excitation (1020 nm) conditions of postsynthetically Eu3+-functionalized material, Pol1-Eu, and discuss its suitability for temperature sensing applications.

Coulomb correlations and two-photon spectra of conjugated polymers

1990 ◽  
Vol 171 (1-2) ◽  
pp. 14-18 ◽  
Author(s):  
Z.G. Soos ◽  
P.C.M. McWilliams ◽  
G.W. Hayden
Keyword(s):  
Conjugated Polymers ◽  
Two Photon ◽  
Photon Spectra ◽  
Coulomb Correlations
Sign in / Sign up

Export Citation Format

Share Document