ePrints@IIScePrints@IISc Home | About | Browse | Latest Additions | Advanced Search | Contact | Help

Second-harmonic generation and electronic structure of polymethineimines: a theoretical study

Albert, IDL and Das, Puspendu K and Ramasesha, S (1991) Second-harmonic generation and electronic structure of polymethineimines: a theoretical study. In: Chemical Physics Letters, 176 (2). pp. 217-224.

[img] PDF
second.pdf - Published Version
Restricted to Registered users only

Download (595kB) | Request a copy
Official URL: http://dx.doi.org/10.1016/0009-2614(91)90157-5


The second-harmonic-generation (SHG) coefficients and properties of low-lying electronic states in polyrnethineimines $(-CH=N-)_x$, up to x= 5 are calculated exactly within the PPP (Pariser-Parr-Pople) Hamiltonian. The $sp^2$ hybridized nitrogenatom parameters for the PPP model are taken from the literature, tested, and found to be satisfactory on pyridine, pyrazine, pyrimidine and s-triazine for which experimental optical gaps are known. The polymethineimines show an optical gapcomparable to that of polyenes and the extrapolated single-strand gap for the infinite polymer is 2.67 eV, slightly smaller than that obtained for polyacetylene. The SHG coefficients in polymethineimines arecomparable to that of the isoelectronic push-pull polyenes with moderately strong electron donors and acceptors. These molecules show a strong length dependence of the SHG coefficient which varies as $L^3^.^0^4$. These results are also valid for the mixed-stack donor-acceptor systems at half-filling.

Item Type: Journal Article
Publication: Chemical Physics Letters
Publisher: Elsevier
Additional Information: Copyright of this article belongs to Elsevier
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 26 Jun 2007
Last Modified: 02 Nov 2010 11:09
URI: http://eprints.iisc.ac.in/id/eprint/11266

Actions (login required)

View Item View Item