Development of a High Sensitivity PumpProbe Fast Scanning

Development of a High. Sensitivity Pump-Probe Fast Scanning Delay Line Stephanie Majewski University of Illinois @ Urbana-Champaign University of Florida Faculty Mentor: Professor David Reitze

Introduction • Femtosecond “LASER”s • Pump-Probe Spectroscopy • Lock-in Method • Fast-Scan System

Femtosecond Lasers 1 fs = 0. 000 000 001 s

What Happens in 100 Femtoseconds? • Light Travels 30 μm • Electrons Collide With Electrons • Solids Begin to Melt Under Laser Irradiation • Chemicals Dissociate There about as many femtoseconds in a minute as there are minutes in the age of the universe.

Project Objectives • Characterize Motion of Shaker • Design Mirror Mount • Optimize Performance of Shaker. Mount System • Implement System in Pump-Probe Experiment

The “Shaker”

Mirror Mount

Obstacles. . . • Elliptical Beam Shape • Unstable Mirror Mount • Wobble in Drive Arm of Shaker

Solutions! • Uniform Bolt Force on Mirror Yielded Circular Beam Shape, Mirror Rattle Minimized • Extra Screw Added Stability to Mount • Beam Jitter Corrected Optically

Time-Resolved Nanotube Transmission Measurement • Achieved successful fast-scan system implementation in pump-probe experiment • Measurement itself unsuccessful due to intrinsic scattering of sample • In future, can try using cross-polarization and other methods to reduce scattering.

Conclusion • Developed Shaker Design for Fast Scanning System • Characterized Shaker Motion and Corrected Beam Jitter to Within Acceptable Limits • Implemented Shaker in Time-Resolved Carbon Nanotube Transmission Measurement

Acknowledgements Professor David Reitze Mark Moores and Anatoly Efimov Drs. Kevin Ingersent and Alan Dorsey NSF Research Experience for Undergraduates