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Anvendt Spektroskopi Applied Spectroscopy KJM3000 Høst 2018

Anvendt Spektroskopi Applied Spectroscopy KJM3000 Høst 2018. Curriculum : - ” Introduction to Spectroscopy ” by Pavia , Lampman , Kriz , Vyvyan All lecture notes All problem sets. Practical information. Lecturer: Tore Bonge-Hansen, rom Ø301, torehans@kjemi.uio.no

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Anvendt Spektroskopi Applied Spectroscopy KJM3000 Høst 2018

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  1. Anvendt Spektroskopi Applied Spectroscopy KJM3000 Høst 2018 Curriculum : - ”Introduction to Spectroscopy” by Pavia, Lampman, Kriz, Vyvyan • All lecture notes • All problem sets

  2. Practical information Lecturer: Tore Bonge-Hansen, rom Ø301, torehans@kjemi.uio.no Lectures and problems: Berzelius, Wed 10.15 Curie, Thu 12.15 Communication: e-mail and homepage. No Canvas! 80% of the problemsets must be approved/passed in order to take the exam. No grade on the problemsets.

  3. Goal : The student should be able to use spectroscopic methods to determine the constitution of organic molecules. Plan: ca. 20 hours of lectures and ca. 40 hours problem solving. Less focus on theory, more on solving problems. Last problem: Thu 29/11. Exam: 20/12. 4h written exam, letter grade. Four spectroscopic methods : UV/VIS, IR, NMR og MS. These methods give complementary info, and together they are a a very powerful tool for identification and structure elucidation of small amounts (mg) of unknown compounds.

  4. KJM1110 (Org 1) exam 2017 MF: C7H12O3 IR: 1723 and 1733

  5. NMR-spectroscopyKjernemagnetisk resonans • History • Physical requirements • Principles • Theory • Interpretation of spectra

  6. History • 1946: NMR discovered • 1949: Chemical shift • 1953: First commercial high resolution instrument • 1960: Structure determination of organic molecules • 1970: FT-NMR • 1971 – 75 : 2D-NMR • 1973: MR-tomography

  7. An old example (CW)

  8. Schematic diagram of NMR

  9. Physical requirements 1.Nuclear spin (12C and 16O are NMR silent) Magnetic moment 2. Magnetic field Number of spin states in the presence of a magnetic field = 2I +1 1H and 13C # spin states = 2 2H # spin states = 3

  10. ΔE = hν ν = γB0/2π ν = frequency, B0 = applied magnetic field, γ = magnetogyric ratio

  11. N1 = number of nuclei in the α state N2 = number of nuclei in the β state N1/N2 is given by Boltzmann’s distribution: At 60 MHz: excess in α state is 9 nuclei in a population of 2 million. The N1/N2 ratio increases with increasing B0.

  12. Net magnetisation vector

  13. FT-NMR

  14. Magnetic field data

  15. Properties

  16. Sample preparation

  17. Chemical shift

  18. Electron density

  19. δ-scale Tetramethylsilane, Si(Me)4 is used as reference in both 1H and 13C TMS: - The nuclei are strongly shielded and appear to the right - 12 1H and 4 13C nuclei - One singel peak - Chemically inert - Non toxic

  20. Carbon 13 and proton

  21. Integration

  22. Integration CW(1H): The area is proportional to the number of nuclei in the peak FT(1H): Same as CW given that the relaxtion time is long enough (2-3 s) FT(13C): Not commonly used due to slow relaxtion and large difference in relaxtion rates for different 13C nuclei.

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