報告摘要:

The scanning tunneling microscope (STM) has enabled us to “see” and move single atoms. STM relies on vacuum tunneling with an exponential increase of a tunneling current between two biased conductive electrodes at a factor of ten per Å (100 pm). The monotonic decrease of current allows us to scan the tip across a sample with atomic precision. In 1986, Binnig, Gerber and Quate introduced atomic force microscopy (AFM), a method that also images insulators by relying on forces. Today, AFM exceeds STM in spatial resolution by utilizing Pauli repulsion forces that change even stronger with distance than the tunneling current. That progress was enabled by qPlus sensor,¹a quartz force sensor that measures force gradients by frequency changes with outstanding precision, which was initially based on tuning forks in Swatch wristwatches. Using qPlus, we can measure the forces that act in atomic manipulation, measure exchange interactions with sub-pN sensitivity, image metal clusters (see figure) and molecules with atomic resolution and single adatoms with subatomic resolution.Conductive tips allow to measure the tunneling current and the forces, including spin dependent forces³and the influence of tip-sample forces on the eigenfrequencies of molecules that are detected by inelastic electron tunneling spectroscopy.⁴An exciting possibility of AFM with qPlus sensors is its capability to obtain subatomic resolution, i.e. the measurement of the angular dependence of chemical bonding forces shown in Fig. C. The quantum corral, introduced by Crommie, Lutz and Eigler in 1993, was revisited by AFM in 2021, showing that the 102 electrons that the corral contains can be viewed as the shell of a two-dimensional atom with similar bonding properties to AFM tips as a natural atom.⁶

(A).qPlus sensor.(B).AFM image of a Fe trimer next to a Fe dimer on Cu(111).(C).AFM image of a single Fe atom on Cu(111).^2,5(D).Quantum corral with one perturbing atom.⁶

References

1. F. J. Giessibl,Rev. Sci. Instrum.90, 011101 (2019).

2. M. Emmrich et al.,Science348308 (2015).

3. F. Pielmeier et al.,Phys. Rev. Lett.110266101 (2013).

4. N. Okabayashi et al.,PNAS1154571 (2018).

5. F. Huber et al.,Science366235 (2019).

6. F. Stilp et al.,Science3721196 (2021).

報告人簡介：

Franz J. Giessibl教授是國際著名的掃描探針顯微學專家，他博士期間曾師從諾貝爾物理學獎和卡夫利獎獲得者Gerd Binnig教授（掃描隧道顯微鏡和原子力顯微鏡發明者之一），目前是德國雷根斯堡大學實驗與應用物理系的講席教授、美國物理學會會士。Giessibl教授是非接觸式原子力顯微鏡（noncontact-atomic force microscope, nc-AFM）領域的開創者，代表性成果包括：搭建了首台低溫超高真空AFM系統；首次基于nc-AFM技術實現了矽表面的原子級成像；發明了qPlus型原子力傳感器并獲得了亞原子級的超高空間分辨；奠定了nc-AFM成像原理的理論基礎等。Giessibl教授1998至2021年期間擔任著名AFM制造商Nanosurf AG的董事會成員，其發明的qPlus型原子力傳感器在世界範圍被廣泛應用于商用化和自主研發的AFM系統中。

Giessibl教授曾獲得過多項獎項，其中包括1994年世界百大研發獎（R&D 100 Award）、2014年美國物理學會約瑟夫·吉時利測量科學進步獎（Joseph F. Keithley Award for Advances in Measurement Science）、2015年德國真空學會魯道夫·雅克爾獎（Rudolf-Jaeckel Prize）、2016年美國前瞻學會費曼納米科技獎（Feynman Prize in Nanotechnology）、2024年日本表面科學學會和IBM研究中心海因裡希·羅雷爾獎章（Heinrich Rohrer Grand Medal），和2024年日本國立物質科學研究所獎（National Institute For Materials Science Award）等著名獎項。

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