Single-Molecule AFM Cantilever for THz Force Detection
Abstract/Contents
- Abstract
- Increasing the resonance frequency of an Atomic Force Microscope (AFM) cantilever is necessary to effectively probe short-range chemical forces. Current AFM cantilevers have frequencies of about 100−200 kHz, limiting the minimum force-gradient that can be measured to the order of 10 pN/nm. This study demonstrates the ability of Inelastic Tunneling Spectroscopy (IETS) to probe THz vibrational modes of a single CO molecule attached to the tip of a low-temperature Scanning Tunneling Microscope (STM). Using molecular manipulation, a CO molecule is transferred to the end of the STM tip and lock-in techniques are used to measure 𝑑2𝐼/𝑑𝑉2 tunneling spectra. Shifts in the frequency of specific vibrational modes of the CO molecule are analyzed as a function of the tip-to-sample distance. This shows that a single molecule can be used as an AFM cantilever for force spectroscopy with the ability to measure small force-gradients to the order of 10−6 pN/nm. IETS with a CO terminated STM tip is also performed over adsorbed CO molecules on a Cu(111) surface revealing a novel vibrational mode due to coupling between the two CO molecules. In future, the small force-gradients detected by STM-IETS can be used to resolve single atoms within a molecule to reveal additional molecular structure.
Description
Type of resource | text |
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Date created | 2010 |
Creators/Contributors
Author | Mahmood, Fahad | |
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Primary advisor | Manoharan, Harindran C. (Harindran Chelvasekaran) "Hari" | |
Advisor | Moler, Kathryn | |
Department | Stanford University, Department of Physics |
Subjects
Subject | Atomic Force Microscope (AFM) |
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Subject | Inelastic Tunneling Spectroscopy (IETS) |
Genre | Thesis |
Bibliographic information
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- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Preferred citation
- Preferred Citation
- Mahmood, Fahad (2010). Single-molecule AFM cantilever for THz force detection. Stanford Digital Repository. Available at http://purl.stanford.edu/cy977mf7313.
Collection
Undergraduate Theses, Department of Physics
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