研究目的
Investigating the controlled switching of a single CuPc molecule on Cu(111) at low temperature through tunneling current measurements and density functional calculations.
研究成果
The study demonstrates a controllable bias-dependent switching of isolated Cu-phthalocyanine molecules chemisorbed on the Cu(111) surface based on conformational changes. The molecules can be prepared in their minimum energy configuration or metastable ones, rotated by ±7?, by applying an appropriate bias voltage. The underlying switching mechanism and the control of rotation direction require further investigation.
研究不足
The study is limited to low temperature conditions (5 K) and requires a specific setup with a commercial LT-STM/AFM. The mechanism of switching in dependence of the voltage sweep direction and the extent to which the rotation direction can be controlled by the scan direction in repeated scans at reversed voltages remains to be investigated.
1：Experimental Design and Method Selection:
Low temperature STM measurements were performed to study the tunneling current as a function of applied bias voltage above individual CuPc molecules on a Cu(111) surface. Density functional theory (DFT) calculations including van der Waals interactions were used to reveal the underlying conformations.
2：Sample Selection and Data Sources:
Individual CuPc molecules adsorbed on a Cu(111) surface were studied. The Cu(111) surface was prepared by several cycles of Ar+ sputtering and subsequent annealing. CuPc molecules were thermally deposited onto the substrate.
3：List of Experimental Equipment and Materials:
A commercial LT-STM/AFM from Omicron Nanotechnology was used at 5 K, with a base pressure of <10?10 mbar, equipped with a qPlus sensor for STM measurements. The tungsten tip was decorated with Cu atoms.
4：Experimental Procedures and Operational Workflow:
Tunneling current data were extracted from a three-dimensional spectroscopy data set acquired on a predefined grid above the surface. Current sampling time per pixel at each position and voltage was 50 ms.
5：Data Analysis Methods:
The data were analyzed to observe the switching behavior of the molecule between two configurations, supported by DFT calculations to understand the underlying conformations.
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