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U Toronto, February 18, 2011Darin 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 2 Noisy Light Spectroscopy Outline I.Introduction II.Theory III. Experiment Coherent Raman Scattering IV. Connections

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 3 Noisy Light Spectroscopy Spectroscopy Using light to gain information about matter Lineshape function Transition frequencies Cross-sections Susceptibilities InformationUses of information In Chemistry In Biology In Engineering

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U Toronto, February 18, 2011Darin 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

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U Toronto, February 18, 2011Darin 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

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U Toronto, February 18, 2011Darin 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!

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 5 Noisy Light Spectroscopy Light frequency Spectrum time One frequency (or color) Electromagnetic radiation Focus on electric field part

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 6 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

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U Toronto, February 18, 2011Darin 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…

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 8 Noisy Light Spectroscopy Theory Optical coherence theory Perturbation theory: Density operator Noisy Light Spectroscopy

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U Toronto, February 18, 2011Darin 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.

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 10 Noisy Light Spectroscopy Bichromophoric Model Noisy light P(t)P(t) (3) P(s)P(s) (3) * Solution Factorized time correlation (FTC) diagram analysis

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 11 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 12 Noisy Light Spectroscopy Example: I (2) CARS P(t,{t i }) P(s,{s i }) arrow segments: -dependent correlation line segments: -independent correlation

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 13 Noisy Light Spectroscopy Experiment Coherent Raman Scattering: e.g., CARS Frequency resolved signals Spectrograms Molecular liquids

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 14 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 15 Noisy Light Spectroscopy CARS Coherent Anti-Stokes Raman Scattering RR 11 11 22 CARS 1 - 2 = R CARS = 1 + R

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 16 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 17 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 18 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 19 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 20 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.

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 21 Noisy Light Spectroscopy I (2) CARS: Data Processing Fourier Transformation X -Marginal

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 22 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.

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 23 Noisy Light Spectroscopy Pyridine and Water FT Neat Pyridine Pyridine/ Water X w = 0.55

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 24 Noisy Light Spectroscopy Pyridine and Water Wavenumber / cm -1

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 25 Noisy Light Spectroscopy Pyridine and Water

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 26 Noisy Light Spectroscopy Halogen bonding

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 27 Noisy Light Spectroscopy Prospectus Summary: Noisy light provides an alternative method for probing ultrafast dynamics of the condensed phase. Experimentally it is relatively easy. Theoretically it is relatively hard. FTC diagram analysis helps with theoretical understanding.

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 28 Noisy Light Spectroscopy Prospectus Future of noisy light at Concordia: I (2) CARS is an exquisitely sensitive probe of vibrational frequency shifts A principle goal is to explore halogen bonding. I (2) CARS is one tool available to us.

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 29 Noisy Light Spectroscopy Connections Coherent Energy Transfer: Noisy light can produce a nonlinear response. Noisy light is “incoherent.” Amplitude level correlation.

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 30 Noisy Light Spectroscopy Connections P(t)P(t) P(s)P(s) Stimulus “Reaction Center”

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College 31 Noisy Light Spectroscopy Acknowledgements Former Students Theory Jahan Dawlaty Dan Biebighauser John Gregiore Duffy Turner Other Group Members Dr. Mark Gealy, Department of Physics Dr. Eric Booth, Post-doctoral researcher Dr. Haiyan Fan, Post-doctoral researcher Funding NSF CAREER Grant CHE Henry Dreyfus Teacher/Scholar program Concordia Chemistry Research Fund Method Development Pye Phyo Aung Tanner Schulz Lindsay Weisel Krista Cosert Perrie Cole Alex Harsh Britt Berger Zach Johnson Thao Ta Hydrogen/Halogen bonding Eric Berg Jeff Eliason Diane Moliva Jason Olson Scott Flancher Danny Green

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U Toronto, February 18, 2011Darin J. Ulness, Concordia CollegeNoisy Light Spectroscopy

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U Toronto, February 18, 2011Darin 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.

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U Toronto, February 18, 2011Darin 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

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U Toronto, February 18, 2011Darin 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

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College A4 Noisy Light Spectroscopy s S/N (a) s D S/N (b)

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College A5 Noisy Light Spectroscopy

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College A6 Noisy Light Spectroscopy

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U Toronto, February 18, 2011Darin J. Ulness, Concordia College A7 Noisy Light Spectroscopy - ∆G° Product Favored - ∆H° Exothermic - ∆S° Entropically unfavorable

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U Toronto, February 18, 2011Darin 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

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