Michael W. Tausch Havana Varadero June, 2015 Photoprocesses in Chemical Education Scientific Talk: Towards Photocatalytic CO 2 Reduction University Chemistry of Wuppertal Education Program Curriculum Innovation I: Why photoprocesses? II: Didactical Credo III: Experiments & Concepts Outline:
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Havana Varadero Photoprocesses · (KOH + DMSO + Luminol) ... Chemoluminescence Color by absorp-tion of light LB VB e-LB VB angeregter Zustand e-e e-e hQ Grundzustand
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Michael W. Tausch
Havana
VaraderoJune, 2015
Photoprocessesin Chemical Education
Scientific Talk: Towards Photocatalytic CO2 Reduction
University Chemistry
of Wuppertal Education
Program
Curriculum Innovation
I: Why photoprocesses?
II: Didactical Credo
III: Experiments & Concepts
Outline:
Innovative Contents ► Experiments ► Teaching Concepts ► Printed and Eletronic Media
Photoprocesses in
Science Education
„It is now clear that electronically excited states of molecules
are the heart of all photoprocesses.The excited state is in fact
an electronic isomer of the ground state.“N. J. Turro, Modern Molecular Photochemistry. Benjamin/Cummings, N.Y. (1978)
Chemical education … deals with the metamorphosis of how to teach chemistry
„A pretty Experiment quite often is more precious than twenty
equations bred in the thinking retort.“A. Einstein, 1955
„Chemistry … deals with the metamorphosis of matter“A. F. Kekulé, 1855
E = mc2
Photoprozesse in der Lehre
der Naturwissenschaften
Light
S1→S0T1→S0
Luminescence: F, P, CL, EL, ECL
Energy transfer
Elektron transferFurther reaction
types
Isomerization
Photovoltaics
Photoprocesses in
Science Education
Requirements for a „pretty“ Experiment: ►appealing & beautiful ► instant & inexpansive
►secure & clean ► innovative & grean ► …
►didactically concise & scientifically consistent
Photoprocesses in
Science Education
Paradigm: Atomic and molecular systems can exist in the electronic ground state
as well as (even for a short time) in electronically excited states.
M.Tausch, M. v. Wachtendonk , C. Bohrmann-Linde, S. Krees (Hrsg.), CHEMIE 2000+, C.C.Buchner, Bamberg (2007…2014)
The energy level model for molecules – A core concept in chemistry
excited state T1
τ = 10-2 – 102 s
excited state S1
τ = 10-9 – 10-8 s
Fluorescence
Phosphorescence
Exchange
of heat
lowest
unoccupied
energy level
highest
occupied
energy level
ground state So
M.T., D. Paterkiewicz, PdN-Chemie 36, 14 (1988); M.T., A. Grolmuss, M. Woock, PdN-Physik 47, 10 (1998); M.T., F.Gärtner, PdN-ChiS, 53, 20 (2004)
Photoprocesses in
Science Education
www.chemiedidaktik.uni-wuppertal.de > Vorträge; oder > Teaching Photochemistry