From Ordinary to Blue Emission in Peralkylated n-Oligosilanes: The Calculated Structure of Delocalized and Localized Singlet Excitons

Autor:	Josef Michl, Matthew K. MacLeod
Rok vydání:	2014
Předmět:	Delocalized electron symbols.namesake Valence (chemistry) Atomic orbital Chemistry Excited state Stokes shift symbols Singlet state Physical and Theoretical Chemistry Dihedral angle Atomic physics Ground state
Zdroj:	The Journal of Physical Chemistry A. 118:10538-10553
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp504805y
Popis:	Excited singlet state structures believed to be responsible for the Franck-Condon-allowed and the strongly Stokes-shifted (blue) emissions in linear permethylated oligosilanes (Si(n)Me(2n+2)) have been found and characterized with time-dependent density functional (TD-DFT) methods for chain lengths 4 ≤ n ≤ 16. For chain lengths with n > 7, the S1 relaxed structures closely resemble the S0 equilibrium structures where all valence angles are tetrahedral and all backbone dihedral angles are transoid. At chain lengths with n < 8 more strongly distorted structures with one long Si-Si bond built from silicon 3p orbitals are encountered. The large Stokes shift is due more to a large destabilization of the ground state than the relaxation in the S1 excited state. For n = 7, both types of minima were located, exactly reproducing the borderline between the large-radius and the small-radius self-trapped excitons known from experiments.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::bd0ca299188098e9e282609189836c5e https://doi.org/10.1021/jp504805y Zobrazit plný text záznamu