Understanding the Effects of Sample Preparation on the Chemical Structures of Petroleum Imaged with Noncontact Atomic Force Microscopy

2018 ◽  
Vol 57 (46) ◽  
pp. 15935-15941 ◽  
Author(s):  
Yunlong Zhang ◽  
Bruno Schuler ◽  
Shadi Fatayer ◽  
Leo Gross ◽  
Michael R. Harper ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Preparation ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Atomic Force

scholarly journals Understanding the Effects of Sample Preparation on the Chemical Structures of Petroleum Imaged with Non-contact Atomic Force Microscopy

2018 ◽  
Author(s):  
Yunlong Zhang ◽  
Bruno Schuler ◽  
Shadi Fatayer ◽  
Leo Gross ◽  
Michael R. Harper ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Preparation ◽  
Structural Integrity ◽  
Bulk Sample ◽  
Molecular Architecture ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Preparation Conditions ◽  
Atomic Force ◽  
Key Characteristics

This study addresses the effect of sample preparation conditions on the structural integrity and composition of heavy hydrocarbon mixtures imaged by non-contact atomic force microscopy (nc-AFM). We designed and prepared a set of organic molecules mimicking well-accepted key characteristics of heavy oil asphaltenes including molecular architecture, molecular weight, boiling point, atomic H/C ratio and bond strength. We deliberately focused on multi-core molecule structures with long aliphatic linkers as this architecture was largely absent in previous nc-AFM studies of petroleum samples. The results confirm that all these molecules can be successfully imaged and remain intact under the same preparation conditions. Moreover, comparison with ultra-high resolution FT ICR-MS of a steam-cracked tar asphaltene sample suggests that the single molecules identified by nc-AFM span the entire molecule spectrum of the bulk sample. Overall, these results suggest that petroleum molecules within the scope of chosen molecules studied herein can be prepared intact and without bias and the imaged data can be representative.

scholarly journals Understanding the Effects of Sample Preparation on the Chemical Structures of Petroleum Imaged with Non-contact Atomic Force Microscopy

2018 ◽  
Author(s):  
Yunlong Zhang ◽  
Bruno Schuler ◽  
Shadi Fatayer ◽  
Leo Gross ◽  
Michael R. Harper ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Preparation ◽  
Structural Integrity ◽  
Bulk Sample ◽  
Molecular Architecture ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Preparation Conditions ◽  
Atomic Force ◽  
Key Characteristics

This study addresses the effect of sample preparation conditions on the structural integrity and composition of heavy hydrocarbon mixtures imaged by non-contact atomic force microscopy (nc-AFM). We designed and prepared a set of organic molecules mimicking well-accepted key characteristics of heavy oil asphaltenes including molecular architecture, molecular weight, boiling point, atomic H/C ratio and bond strength. We deliberately focused on multi-core molecule structures with long aliphatic linkers as this architecture was largely absent in previous nc-AFM studies of petroleum samples. The results confirm that all these molecules can be successfully imaged and remain intact under the same preparation conditions. Moreover, comparison with ultra-high resolution FT ICR-MS of a steam-cracked tar asphaltene sample suggests that the single molecules identified by nc-AFM span the entire molecule spectrum of the bulk sample. Overall, these results suggest that petroleum molecules within the scope of chosen molecules studied herein can be prepared intact and without bias and the imaged data can be representative.

Optimal sample preparation for nanoparticle metrology (statistical size measurements) using atomic force microscopy

2009 ◽  
Vol 12 (3) ◽  
pp. 939-949 ◽  
Author(s):  
Christopher M. Hoo ◽  
Trang Doan ◽  
Natasha Starostin ◽  
Paul E. West ◽  
Martha L. Mecartney
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Preparation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Optimal Sample

scholarly journals Identify Similarities in Diverse Polycyclic Aromatic Hydrocarbons of Asphaltenes and Heavy Oils Revealed by Noncontact Atomic Force Microscopy: Aromaticity, Bonding, and Implications in Reactivity

2019 ◽  
Author(s):  
Yunlong Zhang
Keyword(s):  
Atomic Force Microscopy ◽  
Aromatic Hydrocarbons ◽  
Molecular Structures ◽  
Polynuclear Aromatic Hydrocarbons ◽  
Heavy Oils ◽  
Diverse Range ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Atomic Force ◽  
Polycyclic Aromatic

Heavy oils are enriched with polycyclic (or polynuclear) aromatic hydrocarbons (PAH or PNA), but characterization of their chemical structures has been a great challenge due to their tremendous diversity. Recently, with the advent of molecular imaging with noncontact Atomic Force Microscopy (nc-AFM), molecular structures of petroleum has been imaged and a diverse range of novel PAH structures was revealed. Understanding these structures will help to understand their chemical reactivities and the mechanisms of their formation or conversion. Studies on aromaticity and bonding provide means to recognize their intrinsic structural patterns which is crucial to reconcile a small number of structures from AFM and to predict infinite number of diverse molecules in bulk. Four types of PAH structures can be categorized according to their relative stability and reactivity, and it was found that the most and least stable types are rarely observed in AFM, with most molecules as intermediate types in a subtle balance of kinetic reactivity and thermodynamic stability. Local aromaticity was found maximized when possible for both alternant and nonalternant PAHs revealed by the aromaticity index NICS (Nucleus-Independent Chemical Shift) values. The unique role of five-membered rings in disrupting the electron distribution was recognized. Especially, the presence of partial double bonds in most petroleum PAHs was identified and their implications in the structure and reactivity of petroleum are discussed.

Application of Atomic Force Microscopy on Studying Micro- and Nano-Structures of Starch

2008 ◽  
Vol 4 (7) ◽  
Author(s):  
Peng Liu ◽  
Ling Chen ◽  
Penny A Corrigan ◽  
Long Yu ◽  
Zhongdong Liu
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Preparation ◽  
Present Situation ◽  
Starch Granules ◽  
Force Microscopy ◽  
Atomic Force ◽  
Nano Structures

This paper reviews the application of atomic force microscopy (AFM) to the study of starch structures, including both macrostructure of starch granules and the nanostructure of molecular chains. It introduces the different techniques of sample preparation and discusses what AFM could observe. The paper summarises the present situation of the application of AFM in the study of starch structures and guides the direction for further research.

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