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Full-Text Articles in Chemistry

Unspecified Verticality Of Franck-Condon Transitions, Absorption And Emission Spectra Of Cyanine Dyes, And A Classically Inspired Approximation, Joseph D. Alia, Joseph A. Flack Nov 2020

Unspecified Verticality Of Franck-Condon Transitions, Absorption And Emission Spectra Of Cyanine Dyes, And A Classically Inspired Approximation, Joseph D. Alia, Joseph A. Flack

Chemistry Publications

The computed vertical energy, Ev,a/f, from the equilibrium geometry of the initial electronic state is frequently considered as representative of the experimental excitation/emission energy, Eabs/fl = hc/λmax. Application of the quantum mechanical version of the Franck–Condon principle does not involve precise specification of nuclear positions before, after, or during an electronic transition. Moreover, the duration of an electronic transition is not experimentally accessible in spectra with resolved vibrational structure. It is shown that computed vibronic spectra based on TDDFT methods and application of quantum mechanical FC analysis predict Eabs = hc/λmax …


Chemical Reasoning Based On An Invariance Property: Bond And Lone Pair Pictures In Quantum Structural Formulas, Joseph D. Alia Jul 2010

Chemical Reasoning Based On An Invariance Property: Bond And Lone Pair Pictures In Quantum Structural Formulas, Joseph D. Alia

Chemistry Publications

Chemists use one set of orbitals when comparing to a structural formula, hybridized AOs or NBOs for example, and another for reasoning in terms of frontier orbitals, MOs usually. Chemical arguments can frequently be made in terms of energy and/or electron density without the consideration of orbitals at all. All orbital representations, orthogonal or not, within a given function space are related by linear transformation. Chemical arguments based on orbitals are really energy or electron density arguments; orbitals are linked to these observables through the use of operators. The Valency Interaction Formula, VIF, offers a system of chemical reasoning based …