Chemical structure imaging of a single molecule by atomic force microscopy at room temperature

Abstract

Atomic force microscopy is capable of resolving the chemical structure of a single molecule on a surface. In previous research, such high resolution has only been obtained at low temperatures. Here we demonstrate that the chemical structure of a single molecule can be clearly revealed even at room temperature. 3,4,9,10-perylene tetracarboxylic dianhydride, which is strongly adsorbed onto a corner-hole site of a Si(111)–(7 × 7) surface in a bridge-like configuration is used for demonstration. Force spectroscopy combined with first-principle calculations clarifies that chemical structures can be resolved independent of tip reactivity. We show that the submolecular contrast over a central part of the molecule is achieved in the repulsive regime due to differences in the attractive van der Waals interaction and the Pauli repulsive interaction between different sites of the molecule.

Measuring the reactivity of a silicon-terminated probe

“…results with support from ab initio density functional theory (DFT) calculations and compare our data to simulations investigating the interaction of metal and silicon clusters with carbon nanotubes [12,13] and recent intramolecular imaging results on semiconductor substrates [2,4].…”

“…Very recently it has been shown that similar contrast can also be obtained on semiconductor surfaces at liquid nitrogen temperatures [2,3] and even at room temperature [4]. In experiments conducted on metallic surfaces it is widely assumed that intramolecular resolution can only be obtained via functionalization of the scanning probe tip with an unreactive atom or molecule, since otherwise the high reactivity of the metallic tip causes manipulation of the molecule before the tip is able to enter into the Pauli repulsion regime where intramolecular contrast is obtained.…”

“…In experiments conducted on metallic surfaces it is widely assumed that intramolecular resolution can only be obtained via functionalization of the scanning probe tip with an unreactive atom or molecule, since otherwise the high reactivity of the metallic tip causes manipulation of the molecule before the tip is able to enter into the Pauli repulsion regime where intramolecular contrast is obtained. However, in recent combined experimental and theoretical studies, it has been suggested that semiconductor tips may counterintuitively be able to provide similar resolution [2][3][4], despite silicon traditionally being thought of as a highly reactive tip material [5][6][7].…”

Techniques to assess bone ultrastructure organization: orientation and arrangement of mineralized collagen fibrils

“…A force-feedback loop has the task of keeping the interaction force between the tip and the sample constant, by acting on the z-piezoelectric element: when the force deviates from the set value, the element moves the sample (or the tip) accordingly, so that the force goes back to the pre-assigned levels. AFM spatial resolution capabilities are impressive and are only comparable with TEM among the techniques considered in this review: it can reach spatial resolutions in the sub-nanometre range, in biological samples and even at room temperature [249]. In addition, AFM can act as a nanoindentation tool to rsif.royalsocietypublishing.org J. R. Soc.…”

Calculating the Entropy Loss on Adsorption of Organic Molecules at Insulating Surfaces

“…[16][17][18][19][20][21][22][23][24] Adsorption geometries in particular can be investigated using scanning probe methods such as non-contact atomic force microscopy (NC-AFM). [25][26][27] However, achieving high resolution in NC-AFM images at room temperature is still a challenge 28 and often the interpretation of images down to an atomistic level requires a detailed understanding of the tip-sample interactions. [29][30][31] Theoretical calculations can provide a better understanding of adsorption geometries, film structures and nucleation sites.…”