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An introduction to the Pigment Research Project Light, Color and Pigments

An introduction to the Pigment Research Project Light, Color and Pigments. Chemistry 123 Spring 2008 Dr. Woodward. Ohio REEL Project Research Experiences to Enhance Learning. Partner Institutions University of Akron (UA) Bowling Green State University (BGSU) Capital University (CU)

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An introduction to the Pigment Research Project Light, Color and Pigments

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  1. An introduction to the Pigment Research ProjectLight, Color and Pigments Chemistry 123 Spring 2008 Dr. Woodward

  2. Ohio REEL ProjectResearch Experiences to Enhance Learning Partner Institutions University of Akron (UA) Bowling Green State University (BGSU) Capital University (CU) Central State University (CtlSU) University of Cincinnati (UC) Cleveland State University (CSU) Columbus State Community College (CSCC) University of Dayton (UD) Kent State University (KSU) Miami University of Ohio (MU) Ohio University (OU) University of Toledo (UT) Wright State University (WSU) Youngstown State University (YSU) The Ohio State University (OSU) http://ohio-reel.osu.edu/ Supported by the National Science Foundation

  3. How does a research module differ from a “normal” lab • Research exploration • Outcome is not known in advance • Involves all phases of the research process • Form a hypothesis • Conduct experiments to test hypothesis • Interpret & report results • Modify hypothesis • Tackles problems of societal interest • Chemistry plays a central role in many challenges facing society • Builds on previous experiments • The details of the experiment evolve from year to year

  4. Research Timeline REEL-I: Use X-ray fluorescence (XRF) and X-ray powder diffraction (XRPD) to identify an unknown salt REEL-II: Use UV-Visible (UV-Vis) spectroscopy to probe the electronic structures of transition metal complexes in solution REEL-III: Use solid state reactions to prepare pigments, characterize the composition, crystal structure and electronic structure of the pigments using XRF, XRPD and UV-Vis methods. REEL-IV: Build on the ideas developed in REEL-III to prepare and characterize inorganic pigments of your own design.

  5. Logistics • Research will be conducted in teams • Students will work in teams (~4 students per team) • Research will be pursued collaboratively • Dr. Woodward & Dr. Stoltzfus • REEL Lab Coordinator (Harry Seibel) • Teaching Assistants • Peer Mentors • Research presentation • Each research group will present their results at one of three REEL poster presentations (May 20,21,22) • Research documentation and reporting • Each student will prepare a report in the form of a scientific paper to describe their research findings

  6. Peer Mentors Back Row: Lana Alghotani, Sachin Sharma, Jen Scherer, Alex Paraskos, Eric Smith, Sarah Watson, Ashley Doles, Derek Heimlich, David Albani, Front Row: Jalpa Patel, Sam Karnitis, Gina Aloisio, Stephen Smith, Brittany Thompson, Ravi Rajmohon, Ken Verdell, Amy Ullman, Amy Tucker, and Kristen Brandt

  7. Experimental Methods • Synthesis • Direct solid state reactions • Characterization • X-ray powder diffraction • X-ray fluorescence • UV-Visible Spectroscopy Ocean Optics UV-Visible Spectrometer (~$7,000) X-ray Powder Diffractometer (~$65,000)

  8. Pigments Pigment:Coloring matter used to make paint. Pigments work by selectively absorbing a portion of the visible light while the remaining visible light is reflected. For more info see http://webexhibits.org/pigments/

  9. Causes of Color • Emitted Light • Blackbody Radiation, Incandesence(light bulb, flame) • Gas Discharges/Excitations(neon lights, aurora borealis) • Luminescence(LED’s, fluoresecent lights, chemluminescence) • Steering and/or Interference Effects • Dispersive Refraction(rainbows, prisms) • Scattering(blue sky) • Interference & Diffraction(butterflies, beetles, opals, CD’s) • Absorbed Light • Intra-atomic excitations(Complex ions, gemstones) • Molecular Orbital Excitations(Chlorophyll, organic dyes) • Band to Band Transitions in Semiconductors(CdS, SnS2, HgS) • Interatomic (charge transfer) excitations • Oxoanions (i.e. CrO42−, MnO4−), Pigments (Prussian blue, chrome yellow), gemstones (sapphire) For more info see http://webexhibits.org/causesofcolor/

  10. The Electromagnetic Spectrum Violet Blue Green Yellow Orange Red

  11. Properties of Electromagnetic Radiation (Light)

  12. The Color Wheel UV 100-400 nm 12.4 - 3.10 eV Violet 400-425 nm 3.10 - 2.92 eV Blue 425-492 nm 2.92 - 2.52 eV Green 492-575 nm 2.52 - 2.15 eV Yellow 575-585 nm 2.15 - 2.12 eV Orange 585-647 nm 2.12 - 1.92 eV Red 647-700 nm 1.92 - 1.77 eV Near IR 10,000-700 nm 1.77 - 0.12 eV 1 eV = 1.602  10−19 J

  13. Absorption of Light & Color If absorbance occurs in one region of the color wheel the material appears with the opposite (complimentary color). • a material absorbs violet light Color = Yellow • a material absorbs green light  Color = Red

  14. Absorption of Light & Color If absorbance occurs in multiple regions of the color wheel the material generally takes on a color in the middle of the colors that are not absorbed. • a material absorbs violet, blue and green light Color = Orange • a material absorbs violet and red light  Color = Yellow-Green

  15. UV-Visible Spectroscopy Monochromatic light (light of a single wavelength) is passed through the sample and the amount of light absorbed by the sample is measured.

  16. Color and Cu2+ complexes [Cu(H2O)4]2+ [Cu(NH3)4]2+

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