Sidney Cohen - Video Lecture

Sidney Cohen - Video Lecture

IVS-IPSTA 2020 Online Conference December 13, 2020

Nanomaterials, Thin films, and Surface Science
Afternoon Session

Session chair:
Maya Bar-Sadan

Ben Gurion University of the Negev

Nano-Mechanical/Spectroscopic Characterization of Organic Micro-Inclusions in Flint

Sidney Cohen

Department of Chemical Research Support
Weizmann Institute of Science, Israel


Flint is a siliceous sedimentary deep sea rock produced by marine bacteria activity within a chalky environment under anoxic conditions. During the rock formation process, bacteria are entombed inside a silica gel in the form of micrometer size micro-inclusions. The anoxic conditions, the absence of water and the rapid entombment allow the preservation of this organic material.

Characterizing these organic micro-inclusions impacts on both geological and archeological studies: it is the key to understanding oil formation and maturation
in shales as well as deducing hominin migration patterns. The small size, thickness and irregular morphology of the organic microinclusions make them very difficult to analyze. We have applied several nanoand microscale analyses to study them. Here, we describe results from two scanning probe-based techniques - contact resonance (CR) and nano-IR microscopies. The former measures the mechanical properties of the materials, and the latter gives localized chemical analysis. Preliminary results from both techniques are surprising, and indicate a mechanically robust species with modulus of about 15 GPa, and an unusual protein with α-helix secondary structure.

In this talk the utility of using these cutting-edge nano-techniques will be discussed. Despite the small and irregular size, and rough morphology of these inclusions, it was possible to isolate them from the inorganic surroundings and to characterize their mechanical and chemical characteristics. The results will be discussed in the context of a multi-technique nano- and micro-analysis which together allow piecing together varied and precise information and gain insights on their origin.