Devonian Cephalopods from Alpena in Michigan

189-208http://deepblue.lib.umich.edu/bitstream/2027.42/48175/2/ID010.pd

Silurian Cephalopods of Northern Michigan

19-86http://deepblue.lib.umich.edu/bitstream/2027.42/48169/2/ID004.pd

Scan Free GEXRF in the Soft X ray Range for the Investigation of Structured Nanosamples

Scan free grazing emission X ray fluorescence spectroscopy GEXRF is an established technique for the investigation of the elemental depth profiles of various samples. Recently it has been applied to investigating structured nanosamples in the tender X ray range. However, lighter elements such as oxygen, nitrogen or carbon cannot be efficiently investigated in this energy range, because of the ineffective excitation. Moreover, common CCD detectors are not able to discriminate between fluorescence lines below 1 keV. Oxygen and nitrogen are important components of insulation and passivation layers, for example, in silicon oxide or silicon nitride. In this work, scan free GEXRF is applied in proof of concept measurements for the investigation of lateral ordered 2D nanostructures in the soft X ray range. The sample investigated is a Si3N4 lamellar grating, which represents 2D periodic nanostructures as used in the semiconductor industry. The emerging two dimensional fluorescence patterns are recorded with a CMOS detector. To this end, energy dispersive spectra are obtained via single photon event evaluation. In this way, spatial and therefore angular information is obtained, while discrimination between different photon energies is enabled. The results are compared to calculations of the sample model performed by a Maxwell solver based on the finite elements method. A first measurement is carried out at the UE56 2 PGM 2 beamline at the BESSY II synchrotron radiation facility to demonstrate the feasibility of the method in the soft X ray range. Furthermore, a laser produced plasma source LPP is utilized to investigate the feasibility of this technique in the laboratory. The results from the BESSY II measurements are in good agreement with the simulations and prove the applicability of scan free GEXRF in the soft X ray range for quality control and process engineering of 2D nanostructures. The LPP results illustrate the chances and challenges concerning a transfer of the methodology to the laborator

Additional Notes on Nephriticerina

151-154http://deepblue.lib.umich.edu/bitstream/2027.42/48187/2/ID024.pd

The Color Patterns of Fossil Cephalopods and Brachiopods, with Notes on Gasteropods and Pelecypods

109-150http://deepblue.lib.umich.edu/bitstream/2027.42/48186/2/ID023.pd

Contributions to the Geology of Foxe Land, Baffin Island

19-76http://deepblue.lib.umich.edu/bitstream/2027.42/48183/2/ID020.pd