1. 1 09:05-09:55 am, Wednesday, September 22, 2010 CHEM 8152: Analytical Spectroscopy Smith 1111, University of Minnesota Resonant cavities Gain Threshold population to achieve oscillation Achieving resonance Longitudinal modes Coherence Pulse length / resolution tradeoff Laser pulse characteristics

2. 2 T. Ditmire, American Scientist, 98, 394-401 (2010) 50 th Anniversary: Discovery of the Laser

3. 3 T. Ditmire, American Scientist, 98, 394-401 (2010) Pumping (Absorption) & Stimulated Emission

4. 4 Stimulated Emission

5. 5 T. Ditmire, American Scientist, 98, 394-401 (2010) CW vs. Mode-Locked Laser Mode-Locked = fixed phase

6. 6 Mode-Locked Laser Characteristics

7. 7 Uncertainty principle lower limit: ΔtΔν ~ 5000 fs cm -1 Pulse Length / Resolution Limits

8. 8 T. Ditmire, American Scientist, 98, 394-401 (2010) Chirped Pulse Amplification

9. 9 Femtosecond Stimulated Raman Spectroscopy Kukura, P.; McCamant, D. W.; Mathies, R. A., Annu. Rev. Phys. Chem., 2007, 58, 461-488.

10. 10 Uncertainty principle lower limit: ΔtΔν ~ 5000 fs cm -1 FSRS is capable of attaining ΔtΔν ~ 500 fs cm -1 Possible because observed variables are decoupled Kukura, P., D.W. McCamant, and R.A. Mathies, Femtosecond stimulated Raman spectroscopy. Annu. Rev. Phys. Chem., 2007. 58: p. 461-488. Pulse Length / Resolution Limits

11. 11 Kukura, P., D.W. McCamant, and R.A. Mathies, Femtosecond stimulated Raman spectroscopy. Annu. Rev. Phys. Chem., 2007. 58: p. 461-488.

12. 12 Kukura, P., D.W. McCamant, and R.A. Mathies, Femtosecond stimulated Raman spectroscopy. Annu. Rev. Phys. Chem., 2007. 58: p. 461-488.

13. 13 Pulse Characteristics

14. 14   s Pump Laser Probe Laser I s (0) Gain Medium IpIp I s > I s (0) <I p Femtosecond Stimulated Raman Spectroscopy Kukura, P.; McCamant, D. W.; Mathies, R. A., Annu. Rev. Phys. Chem., 2007, 58, 461-488.

15. 15 FSRS Apparatus 35 fs, 800 nm, 10  J, 250 KHz

16. 16 Accessible Spectral Window, Time Resolution, and Molecular Modes Probed by Vibrational Spectroscopic Techniques Used To Monitor Structural Dynamics Kukura, P., D.W. McCamant, and R.A. Mathies, Femtosecond stimulated Raman spectroscopy. Annu. Rev. Phys. Chem., 2007. 58: p. 461-488.

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