Abstract by Spencer Jeppson
Chemistry and Biochemistry
Normalizing Second-Harmonic Generation Spectroscopy Signals
Optical second-harmonic generation (SHG) spectroscopy may potentially be a powerful, non-destructive tool for probing naval-grade aluminum for sensitization that can lead to dangerous and expensive corrosion. To test this, second harmonic response is measured and compared on aluminum samples before and after sensitization by heat treatment. Heat treatment consists of heating the samples in an oven for several lengths of time between 8 hours and 1 week. The time required to sensitize aluminum means that laser output may vary drastically between measurements, making it difficult to establish a correlation between sensitization and SHG response. The response of a photodiode has been found to be linear with respect to the energy of each laser pulse, allowing measurements made at different times to be normalized to each other. This allows for more significant comparisons between measurements made with differing laser output.