| AVS 58th Annual International Symposium and Exhibition | |
| Applied Surface Science Division | Tuesday Sessions |
| Session AS-TuA |
| Session: | Imaging and 3D Chemical Analysis - Part II |
| Presenter: | Joe Baio, University of Washington |
| Authors: | J.E. Baio, University of Washington C. Jaye, National Institute of Standards and Technology E. Sullivan, Woodland Park Zoo D.A. Fischer, National Institute of Standards and Technology D.G. Castner, University of Washington T. Weidner, University of Washington |
| Correspondent: | Click to Email |
Insect cuticle is a matrix of structural proteins and long chain polymers of chitin. The chemical composition of the cuticle is dictated by the biomechanics of the insect. Regions of the exoskeleton where extra stiffness is required - this matrix become mineralized and form scalarites. Elastic portions of the cuticle are rich with pliable structural proteins. While engineers have set out to copy these biomineralization processes and design materials that mimic the extraordinary structural capabilities of these exoskeletons – a complete understanding of the structure of this chitin/protein/mineral matrix does not currently exist. In this study, we set out to spatially resolve the chemistry, at the cuticle surface, of an African Flower Scarab (Eudicella gralli) by near edge x-ray adsorption fine structure (NEXAFS) imaging. The NEXAFS images are produced by a new parallel process magnetic field electron yield optics detector, and a full field incident soft X-ray beam on the sample. The rapid parallel process magnetic field electron yield optics detector (LARIAT:Large Area Imaging Analytical Tool) produces a series of two-dimensional NEXAFS spatial images as the incident soft X-ray energy is scanned above a K or L absorption edge. A spatially resolved view of cuticle surface chemistry was created by mapping spectral features within the carbon (270-370 eV), nitrogen (380-430 eV), and oxygen (520-580 eV) K-edge spectra. Distributions of protein and chitin rich regions around the beetle were defined by changes in intensity of π*(284.5 eV) and C-H* (290 eV) within the C K-edge spectra. Regions of high mineralization were observed around the edges of the beetle’s head and were assigned by tracking the intensities of the calcium (330-360 eV) and iron (700-740 eV) L-edges. These images also showcase the strengths of NEXAFS imaging, which unlike other photoelectron spectroscopy modalities, allowed us to collect high quality spectra over a large field of view (12 mm x 18 mm ) at a range of x-ray incidence angles, with little beam damage to the tissue.