1. Augustana, March 2, 2007Darin J. Ulness, Concordia College 1 Noisy Light Spectroscopy Noisy Light Spectroscopy: Putting noise to good use Darin J. Ulness Department of Chemistry Concordia College Moorhead, MN The A

2. Augustana, March 2, 2007Darin J. Ulness, Concordia College 2 Noisy Light Spectroscopy Outline I.Introduction II. Experiment Coherent Raman Scattering III. Hydrogen Bonding Pyridine systems IV. Prospectus

3. Augustana, March 2, 2007Darin J. Ulness, Concordia College 3 Noisy Light Spectroscopy Spectroscopy Using light to gain information about matter Transition frequencies Lineshapes Susceptibilities InformationUses of information In Chemistry In Biology In Engineering

4. Augustana, March 2, 2007Darin J. Ulness, Concordia College 4 Noisy Light Spectroscopy Light frequency Spectrum time One frequency (or color) Electromagnetic radiation Focus on electric field part

5. Augustana, March 2, 2007Darin J. Ulness, Concordia College 5 Noisy Light Spectroscopy Noisy Light: Definition Broadband Phase incoherent Quasi continuous wave Noisy Light Spectrum Frequency Time resolution on the order of the correlation time,  c

6. Augustana, March 2, 2007Darin J. Ulness, Concordia College 6 Noisy Light Spectroscopy Experiment Coherent Raman Scattering: e.g., CARS Frequency resolved signals Spectrograms Molecular liquids

7. Augustana, March 2, 2007Darin J. Ulness, Concordia College 7 Noisy Light Spectroscopy Nonlinear Optics P=  E Signal Material Light field Perturbation series approximation P(t) = P (1) + P (2) + P (3) … P (1) =  (1) E, P (2) =  (2) EE, P (3) =  (3) EEE

8. Augustana, March 2, 2007Darin J. Ulness, Concordia College 8 Noisy Light Spectroscopy CARS Coherent Anti-Stokes Raman Scattering RR 11 11 22  CARS  1 -  2 =  R  CARS =  1 +  R

9. Augustana, March 2, 2007Darin J. Ulness, Concordia College 9 Noisy Light Spectroscopy CARS with Noisy Light I (2) CARS We need twin noisy beams B and B’. We also need a narrowband beam, M. The frequency of B (B’) and M differ by roughly the Raman frequency of the sample. The I (2) CARS signal has a frequency that is anti-Stokes shifted from that of the noisy beams. B B’ M I (2) CARS

10. Augustana, March 2, 2007Darin J. Ulness, Concordia College 10 Noisy Light Spectroscopy I (2) CARS: Experiment Monochromator Narrowband Source Broadband Source (noisy light) Lens Sample Interferometer  B B’ M I (2) CARS Computer CCD

11. Augustana, March 2, 2007Darin J. Ulness, Concordia College 11 Noisy Light Spectroscopy I (2) CARS: Spectrogram Monochromator Narrowband Source Broadband Source Lens Sample Interferometer  B B’ M I (2) CARS Computer CCD Signal is dispersed onto the CCD Entire Spectrum is taken at each delay 2D data set: the Spectrogram

12. Augustana, March 2, 2007Darin J. Ulness, Concordia College 12 Noisy Light Spectroscopy I (2) CARS: Spectrogram Pixel A A Pixel B B Pixel C C Dark regions: high intensity Light regions: low intensity Oscillations: downconversion of Raman frequency. Decay: Lineshape function

13. Augustana, March 2, 2007Darin J. Ulness, Concordia College 13 Noisy Light Spectroscopy Spectrogram No new information can be extracted. However… Huge oversampling gives much enhanced precision. Visually appealing presentation of data gives much insight.

14. Augustana, March 2, 2007Darin J. Ulness, Concordia College 14 Noisy Light Spectroscopy I (2) CARS: Data Processing Fourier Transformation X -Marginal

15. Augustana, March 2, 2007Darin J. Ulness, Concordia College 15 Noisy Light Spectroscopy Virtues of I (2) CARS Less expensive. Easier experiment to perform. Signals are more robust. Immune to dispersion effects. Exquisitely sensitive to relative changes in the vibrational frequency and dephasing rate constant.

16. Augustana, March 2, 2007Darin J. Ulness, Concordia College 16 Noisy Light Spectroscopy Hydrogen Bonding Interaction between a hydrogen atom and oxygen or nitrogen (or fluorine) A very weak chemical interaction (bond) A very strong physical interaction Exploited extensively in biological systems O, N H

17. Augustana, March 2, 2007Darin J. Ulness, Concordia College 17 Noisy Light Spectroscopy Pyridine Systems Why Pyridine Simple molecule Important component in many compounds Biological importance Strong I (2) CARS signal H-bond acceptor but not a H-bond donor. N C C C C C H H H H H

18. Augustana, March 2, 2007Darin J. Ulness, Concordia College 18 Noisy Light Spectroscopy Pyridine: Normal Modes 1 990 A1A1 Ring Breathing 12 1030 A1A1 Triangle

19. Augustana, March 2, 2007Darin J. Ulness, Concordia College 19 Noisy Light Spectroscopy Pyridine and H-bonding Neat Pyridine Two peaks With H-bond Three peaks

20. Augustana, March 2, 2007Darin J. Ulness, Concordia College 20 Noisy Light Spectroscopy Pyridine and H-bonding Key Results Some pyridine is free some is hydrogen bonded Hydrogen bonding blue- shifts the ring breathing mode Hydrogen bonding does not shift the triangle mode

21. Augustana, March 2, 2007Darin J. Ulness, Concordia College 21 Noisy Light Spectroscopy Pyridine: Inner Tube Model Molecular orbitals Electrostatics Compare with benzene Stabilization through  delocalization H-bonding makes pyridine more “benzene- like”

22. Augustana, March 2, 2007Darin J. Ulness, Concordia College 22 Noisy Light Spectroscopy Pyridine: Inner Tube Model Electron density for Benzene = + Electron density for free pyridine Electron density for H-bonded pyridine = + Full e - density  e - density sp 2 e - density Full e - density  e - density sp 2 e - density ≈

23. Augustana, March 2, 2007Darin J. Ulness, Concordia College 23 Noisy Light Spectroscopy Pyridine: Test of Model Vary the strength of hydrogen bonding Formamide N-H-N bond ~ 3-4 Kcal/mol Water N-H-O bond ~ 6-7 Kcal/mol Acetic Acid Proton transfer (acid/base) 98099010001010102010301040 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 Normalized X marginal intensity Raman wavenumber / cm Formamide Water Acetic Acid 4 cm -1 8 cm -1 14 cm -1

24. Augustana, March 2, 2007Darin J. Ulness, Concordia College 24 Noisy Light Spectroscopy Pyridine: Peak Broadening

25. Augustana, March 2, 2007Darin J. Ulness, Concordia College 25 Noisy Light Spectroscopy Peak Broadening Models Network model Thermalized distribution model Etc. Fileti, E.E.; Countinho, K.; Malaspina, T.; Canuto, S. Phys. Rev. E. 2003, 67, 061504.

26. Augustana, March 2, 2007Darin J. Ulness, Concordia College 26 Noisy Light Spectroscopy Pyridine/water Temperature 98099010001010102010301040 0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 T = -40 O C T = -20 O C T = 0 O C T = 20 O C T = 40 O C T = 60 O C Normalized X marginal intensity Raman wavenumber / cm Xpy = 0.55

27. Augustana, March 2, 2007Darin J. Ulness, Concordia College 27 Noisy Light Spectroscopy Pyridine/water Temperature Xpy = 0.55 -40-200204060 1.0 1.5 2.0 2.5 3.0 3.5 Peak width (obs) / cm Temperature / O C Hydrogen Bonded Ring Breathing Mode “Free” Pyridine Ring Breathing Mode Triangle Mode

28. Augustana, March 2, 2007Darin J. Ulness, Concordia College 28 Noisy Light Spectroscopy Pyridine/water Temperature Xpy = 0.55

29. Augustana, March 2, 2007Darin J. Ulness, Concordia College 29 Noisy Light Spectroscopy Prospectus Summary: Noisy light provides an alternative method for probing ultrafast dynamics of the condensed phase. Useful tool for probing hydrogen bonding using “test” molecules. Simple model useful in understanding hydrogen bonding in pyridine. Thermalized distribution is likely cause of peak broadening.

30. Augustana, March 2, 2007Darin J. Ulness, Concordia College 30 Noisy Light Spectroscopy Prospectus Future of noisy light at Concordia: Other pyridine based molecules Hydroxymethyl pyridine. Halo pyridines. Other nitrogen heterocycles. A principle goal is to develop an I (2) CARS based microscopy.

31. Augustana, March 2, 2007Darin J. Ulness, Concordia College 31 Noisy Light Spectroscopy Acknowledgements Former Students Jahan Dawlaty: Cornell University, Ph.D. candidate in optical electronics Dan Biebighauser: Vanderbilt University, Ph.D. in mathematics John Gregiore: Cornell University, Ph.D. candidate in physics Duffy Turner: MIT, Ph.D. candidate in physical chemistry Pye Phyo Aung: John’s Hopkins University, Ph.D. candidate in mathematics Tanner Schulz: University of Minnesota, Ph.D. candidate in physics Lindsay Weisel: Michigan State University, Ph.D. candidate in physical chemistry Current Students Britt Berger Zach Johnson Erik Berg Danny Green Sarah Freeman Other Group Members Dr. Mark Gealy, Department of Physics Dr. Eric Booth, Post-doctoral researcher Funding NSF CAREER Grant CHE-0341087 Henry Dreyfus Teacher/Scholar program Concordia Chemistry Research Fund

32. Augustana, March 2, 2007Darin J. Ulness, Concordia CollegeNoisy Light Spectroscopy

33. Augustana, March 2, 2007Darin J. Ulness, Concordia College 23 Noisy Light Spectroscopy Pyridine and Water

34. Augustana, March 2, 2007Darin J. Ulness, Concordia College 7 Noisy Light Spectroscopy Noisy Light: Alternative Its cw nature allows precise measurement of transition frequencies. Its ultrashort noise correlation time offers femtosecond scale time resolution. It offers a different way to study the lineshaping function. It is particularly useful for coherent Raman scattering. Other spectroscopies: photon echo, OKE, FROG, polarization beats…

35. Augustana, March 2, 2007Darin J. Ulness, Concordia College 8 Noisy Light Spectroscopy Theory Optical coherence theory Perturbation theory: Density operator Noisy Light Spectroscopy

36. Augustana, March 2, 2007Darin J. Ulness, Concordia College 9 Noisy Light Spectroscopy Theoretical Challenges Complicated Mathematics Complicated Physical Interpretation Difficulty The cw nature requires all field action permutations. The light is always on. The proper treatment of the noise cross-correlates chromophores. Solution Factorized time correlation (FTC) diagram analysis

37. Augustana, March 2, 2007Darin J. Ulness, Concordia College 10 Noisy Light Spectroscopy FTC Diagram Analysis Set of intensity level terms (pre-evaluated) Set of evaluated intensity level terms Messy integration and algebra Set of FTC diagrams Construction Rules Evaluation Rules Physics hard easy

38. Augustana, March 2, 2007Darin J. Ulness, Concordia College A1 Noisy Light Spectroscopy Utility of FTC Diagrams Organize lengthy calculations Error checking Identification of important terms Immediate information of about features of spectrograms Much physical insight that transcends the choice of mathematical model.

39. Augustana, March 2, 2007Darin J. Ulness, Concordia College A2 Noisy Light Spectroscopy Example: I (2) CARS   P(t,{t i }) P(s,{s i }) arrow segments: B, B’ correlation  -dependent line segments: B, B or B’,B’ correlation  -independent FTC analysis Each diagram with arrows has a topologically equivalent partner diagram containing only lines: 2:1 dynamic range Each diagram with arrows has a topologically equivalent partner diagram that has arrows pointing in the opposite direction: signal must be symmetric in 

40. Augustana, March 2, 2007Darin J. Ulness, Concordia College 4 Noisy Light Spectroscopy Modern Spectroscopy Frequency Domain Measure Spectra Examples IR, UV-VIS, Raman Material response Spectrally narrow Temporally slow Time Domain Response to light pulse Examples PE, transient abs. Material response Spectrally broad Temporally fast

41. Augustana, March 2, 2007Darin J. Ulness, Concordia College 4 Noisy Light Spectroscopy Modern Spectroscopy Frequency Domain Measure Spectra Examples IR, UV-VIS, Raman Material response Spectrally narrow Temporally slow Time Domain Response to light pulse Examples PE, transient abs. Material response Spectrally broad Temporally fast

42. Augustana, March 2, 2007Darin J. Ulness, Concordia College 4 Noisy Light Spectroscopy Modern Spectroscopy Frequency Domain Measure Spectra Examples IR, UV-VIS, Raman Material response Spectrally narrow Temporally slow Time Domain Response to light pulse Examples PE, transient abs. Material response Spectrally broad Temporally fast Is there another useful technique? Noisy light?YES!

43. Augustana, March 2, 2007Darin J. Ulness, Concordia College A3 Noisy Light Spectroscopy Example: I (2) CARS Pixel A A Pixel B B Pixel C C The I (2) CARS data shows 2:1 dynamics range  symmetry

44. Augustana, March 2, 2007Darin J. Ulness, Concordia College A4 Noisy Light Spectroscopy 012345 0.00 0.05 0.10 0.15 0.20 0.25 0.30 s  S/N (a) 012345 0.00 0.05 0.10 0.15 0.20 0.25 0 s  D S/N (b)

45. Augustana, March 2, 2007Darin J. Ulness, Concordia College A5 Noisy Light Spectroscopy

46. Augustana, March 2, 2007Darin J. Ulness, Concordia College A6 Noisy Light Spectroscopy

47. Augustana, March 2, 2007Darin J. Ulness, Concordia College A7 Noisy Light Spectroscopy - ∆G° Product Favored - ∆H° Exothermic - ∆S° Entropically unfavorable

48. Augustana, March 2, 2007Darin J. Ulness, Concordia College A8 Noisy Light Spectroscopy   complex = I complex   free x free I complex = I free at 0.21 mole fraction   complex = 1   free.79   complex = 3.76   free