1. Chemistry 8152: Analytical Spectroscopy Fall 2006 – 4 Credits Smith 111: MWF 11:15 – 12:05 Smith 111: MWF 11:15 – 12:05 Instructor: Christy Haynes 243 Smith Hall 626-1096haynes@chem.umn.edu

2. Let’s vote for preferred office hours: Mondays from 9-10 amMondays from 9-10 am Mondays from 3 – 4 pmMondays from 3 – 4 pm Wednesdays from 1 – 2 pmWednesdays from 1 – 2 pm Fridays from 12 – 1 pmFridays from 12 – 1 pm => Other times may be possible by appointment. Text: No required text. Course notes and hand-outs will be available on the class blog (http://blog.lib.umn.edu/chaynes/8152/). If you know from experience that you learn best when you have a book, consider buying a copy of “Ingle and Crouch”.

3. Other sources that may be useful: James D. Ingle Jr. and Stanley R. Crouch, “Spectrochemical Analysis”, Prentice Hall, New Jersey, 1988. Eugene Hecht, “Optics”, Addison Wesley, New York, 2002. Douglas A. Skoog and James J. Leary, “ Principles of Instrumental Analysis”, Harcourt Brace College Publishing, New York, 1997. Janet D. Dodd, “The ACS Style Guide—A Manual for Authors and Editors”, American Chemical Society, Washington DC, 1997.

4. Class Description: Spectroscopy describes the interaction of electromagnetic radiation and matter. In analytical spectroscopy, one applies spectroscopic techniques to both analyte mixtures and trace samples. In this class, we’ll cover fundamental principles as well as a wide range of contemporary techniques. Learning Objectives: Critically consume scientific literature and talks. Identify appropriate techniques for the analysis of any sample. Recognize strengths/weaknesses of each method.

5. Analytical Seminar Series: 10/2/2006Sang-Hyun Oh Electrical and Computer Engineering 10/9/2006Mary KaiserDuPont 10/16/2006Dwight StollCarr Group 10/23/2006Marian NavratilArriaga Group 11/13/2006Danni LiArriaga Group 11/20/2006Matt SimcikDepartment of Public Health Mondays from 4:15 – 5:15 pm in Smith 331

6. Final Grade Final Grade 2 Exams @ 100 points each200 Cumulative Final Exam200 5 Problem Sets @ 20 points each100 Proposal White Paper and Outline75 Proposal Presentation75 10 Minute papers @ 10 points each100 Total Points Possible750

7. Assignments 09/20Problem set 1 10/11Problem set 2 10/13Midterm #1 11/01Problem set 3 11/22Problem set 4 11/13Midterm #2 12/04Proposal white paper and outline 12/13Problem set 5 12/20 Final Exam *Minute papers due every Friday @ 5 pm (exceptions are Thanksgiving holiday and last week of class)

8. Exams *Two hour exams during the semester (10/13 &11/13). *The final exam on 12/20 (10:30 to 12:30 AM; room TBA) will be comprehensive. 2 hours; 200 points. *No equations will be provided. Bring a calculator. *You may bring one 8.5” x 11” page of equations and notes to each midterm exam. You may bring two 8.5” x 11” pages of equations and notes to the final exam.

9. Problem Sets Each problem set will receive equal weighting in calculating the final grade (total of 100 points). You may work in groups but each person must submit their own solutions. All problem sets are due by 5 pm in my mailbox (A14). Assignments submitted late without a valid excuse will not be graded.

10. Original Proposal *Each person will identify an unexplored analytical chemistry research question and choose appropriate spectroscopic methods to explore this question. *On 12/04/06, each person will turn in a white paper describing their proposed research as well as an outline of the experiments to be done (75 points). *During the last week of class, each person will present a 15 minute talk about their proposed research to the class (75 points).

11. Minute Papers The purpose of the "Minute Paper" assignments is to promote exposure to the scientific literature. Each week, you will choose an article from the ASAP alerts that is relevant to this class to read critically. Write a short summary of the paper you chose and post it as a "comment" under that week's minute paper blog post. The minute paper should be grammatically correct, written in your own words, and no longer than 500 words. You should emphasize the technique that was used and the major findings of the work. Each week, a minute paper is due by Friday at 5 pm. You must complete at least 10 of the 13 minute papers on time in order to receive full credit.

12. Why is Analytical Spectroscopy Important?

13. Spectroscopy … spectro-: light-scope: looking, examining, seeing -graph: recording -meter, -metry: measuring Spectroscopy: Science dealing with interaction of electromagnetic radiation and matter. Spectrometry: Quantitative measurement based on information from a spectrum. Spectrum: Display of the intensity of radiation emitted, absorbed, or scattered by a sample versus a quantity related to photon energy (e.g. wavelength or frequency). Spectrophotometer: Instrument used to provide input light and determine the output light intensity at various wavelengths in the spectrum. Spectrometer: Instrument used determine the output light intensity at various wavelengths in the spectrum.

14. The Fluorescence Experiment: A Typical Spectrochemical Measurement Photomultiplier Tube (Detector/Transducer)

15. Photons Douglas A. Skoog and James J. Leary, Principles of Instrumental Analysis, Saunders College Publishing, Fort Worth, 1992. = frequency is number of waves/unit time = wavelength is number of units of length/wave = wavenumber is number of cycles/unit length

16. Photons Photons are discrete packets of electromagnetic (EM) radiation energy. E = h = (hc) = hc E = energy of photon (joules) h = Planck’s constant (6.63 x 10 -34 Js) = frequency (s -1 ) c = speed of light (3.00 x 10 8 m/s) = wavelength (m) = wavenumber (m -1 )

17. Electromagnetic Spectrum Image Source: http://www.daviddarling.info/encyclopedia/E/emspec.html Primary focus in this class: UV, visible, IR E units = joules or electron volts (1 eV = 1.6 x 10 -19 J) units = nanometers (10 -9 m), micrometers (10 -6 m), or angstroms (1 Å = 10 -10 m) 1 eV of photon energy = radiation with of 1240 nm

18. Are you getting the concept? Calculate the energy of (a) a 5.30 Å X-ray photon (in eVs) and (b) a 530-nm photon of visible radiation (in kJ/mole).

19. Electromagnetic Spectrum The energy of the photon determines the type of transition or interaction that occurs. Table 1-1 – Ingle and Crouch, Spectrochemical Analysis

20. Spectroscopy EM Radiation Sources No radiation: Excitation by collisions or chemical reactions can initiate photon emission. Continuum Source: Emit radiation over a broad wavelength range (e.g. incandescent lamps) Line Source: Emit radiation at discrete wavelengths (e.g. Hg arc lamp, laser). Image source: www.oceanoptics.com Tungsten Halogen Lamp Mercury Argon Lamp

21. Interaction between EM Radiation and the Sample absorbradiationradiationlessabsorptionemitradiationradiationlessemission emissionabsorptionphotoluminescence inelastic excitation or deactivation

22. Atomic vs. Molecular Spectroscopy Atomic Spectroscopy: Purely electronic transitions from outer- shell (valence) electrons. - electronic levels are far apart - electronic levels are far apart - narrow line spectra - narrow line spectra - allowed transitions predicted from quantum mechanics - allowed transitions predicted from quantum mechanics Molecular Spectroscopy: Accessible electronic, vibrational, and rotation transitions. - many rotational and vibrational levels within each electronic level - many rotational and vibrational levels within each electronic level - broad band spectra - broad band spectra - allowed transitions predicted from quantum mechanics - allowed transitions predicted from quantum mechanics

23. Atomic vs. Molecular Spectroscopy Atomic Spectroscopy Example (Cl 2 ): Molecular Spectroscopy (CH 3 CH 2 OH): Image source: www.wikipedia.org

24. Wavelength Selection before Detection Must separate analyte optical signal from a majority of the potentially interfering optical signals. - absorption filters - absorption filters - interference filters - interference filters - spatial dispersion - spatial dispersion - interferometry - interferometry Image source: www.wikipedia.org

25. Are you getting the concept? The two transmission profiles below are for filters sold by Melles-Griot. Which filter would you buy to block = 15,800 cm -1 light? (a)(b)

26. Radiant Power Monitors (a.k.a. Detectors) Detectors convert EM radiation into an electrical signal or another physical quantity that can easily be converted into an electrical signal. Thermal Detectors: convert IR radiation into current or voltage Photon Detectors: convert UV and visible photons into current Multichannel Detectors: convert UV and visible photons into charge Skoog and Leary, Principles of Instrumental Analysis, Saunders College Publishing, Fort Worth, 1992.