Ebrahim Ghanbari

Kerogen as one the main constituents of mud rocks is not thoroughly understood in terms of its mechanical characteristics. Kerogen is not as stiff as inorganic minerals within the rock matrix, but it can have a significant impact on the propagation of fractures. This becomes more important in organic rich shale reservoirs. In this study, first we proposed a fast method to predict mechanical properties of kerogen using Raman spectroscopy, which is a function of its molecular structure and chemical compounds, and then incorporated the results in hydraulic fracturing simulation. FLAC software was used to simulate opening of a fracture in the shaly and kerogen rich members of the Bakken formation. Then results were compared with a shale simple model missing organic matter properties. Results showed organic matter mechanical characteristics affects the hydraulic fracturing simulation by having faster fracture closure and requiring more fracing volume to achieve a specified fracture length compared to the simple model. The proposed method of using Raman spectroscopy can be used to make a profile of mechanical properties of organic matter and then be used in hydraulic fracturing simulation to optimize the operation.

By monitoring the reflectance of a sample surface during deposition of a thin organic film, one can obtain information with submonolayer resolution in real-time. A special kind of optical spectroscopy is Differential Reflectance Spectroscopy (DRS), which compares the reflectance before and during deposition of a thin film or any other change of the surface optical properties. In this work, we present an extended DRS setup that allows monitoring simultaneously both linear polarization states (s and p) of the reflected light. We implement polarization-dependent DRS to monitor the growth of perflouropentacene thin films on a Ag(110) single crystal. The setup allows us to deduce the optical anisotropy of the sample and, in particular, the preferred orientation of the molecules on the surface.

Photoelectron emission microscopy (PEEM) and differential (optical) reflectance spectroscopy (DRS) have proven independently to be versatile analytical tools for monitoring the evolution of organic thin films during growth. In this paper, we present the first experiment in which both techniques have been applied simultaneously and synchronously. We illustrate how the combined PEEM and DRS results can be correlated to obtain an extended perspective on the electronic and optical properties of a molecular film dependent on the film thickness and morphology. As an example, we studied the deposition of the organic molecule α-sexithiophene on Ag(111) in the thickness range from submonolayers up to several monolayers.