Date Thesis Awarded

5-2017

Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)

Department

Physics

Advisor

M. Mumtaz Qazilbash

Committee Members

Gina Hoatson

Hannes Schniepp

Abstract

We want to gain insight into the composition and structure of spider silk to discover the origin of its extremely high mechanical properties. We are especially interested in the organization of the crystalline ß-sheets that are expected to contribute to the high strength of the silk from the recluse spider, Loxosceles laeta. The recluse spider produces a thin, ribbon-like silk, which has a unique geometry amongst arachnids. We measure the silk's optical properties, particularly the infrared-active vibrations. Broadband infrared transmission spectra were collected in the spectral range between 600 cm−1 and 4000 cm−1, with light polarized parallel and perpendicular to the long axis of the silk. The infrared vibrational modes are fit with Lorentzian and Voigt functions. The vibrational modes are assigned to specific structures and electronic bonds in the silk. We find that at least one-fourth of the recluse spider silk consists of crystalline ß-sheets.

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