NCAFM2023 Programme Booklet

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24 th International Conference on Non-contract Atomic Force Microscopy

WELCOME MESSAGE

24th International Conference on Non-contact Atomic Force Microscopy September 25th to 29th 2023, Singapore

NCAFM 2023 is the 24th of a series of conferences devoted to non-contact atomic force microscopy. We aim to bring together a diverse group of researchers from across the world to highlight the most recent advances in the field, covering the experimental, theoretical and instrumental developments in frequency modulation and other dynamic operation modes, with a particular emphasis on aspects of high-resolution imaging and force spectroscopy. Previous conferences were held in Nijmegen , Netherlands (2022), Regensburg , Germany (2019), Porvoo , Finland (2018), Suzhou , China (2017), Nottingham , UK (2016), Cassis , France (2015), Tsukuba , Japan (2014), Maryland , USA (2013), Ceský Krumlov , Czech Republic (2012), Lindau , Germany (2011), Kanazawa , Japan (2010), New Haven , USA (2009), Madrid , Spain (2008), Antalya , Turkey (2007), Kobe , Japan (2006), Bad Essen , Germany (2005), Seattle , USA (2004), Dingle , Ireland (2003), Montreal , Canada (2002), Kyoto , Japan (2001), Hamburg , Germany (2000), Pontresina , Switzerland (1999), Osaka , Japan (1998).

Welcome to Singapore and enjoy the conference!

The organizing committee

COMMITTEE

Sponsors

For over 40 years, Quantum Design has been a leading manu facturer of automated material characterization systems for the physics, chemistry, and material science research commu nities. Since 2016, Quantum Design Singapore prides itself on providing local sales, services and technical supports to researchers in Southeast Asian countries. Quantum Design Park System Park Systems is a world-leading manufacturer of atomic force microscopy (AFM) and nano metrology systems, empowering nanoscale advances for global researchers in semiconductor, materials, life sciences, physics, chemistry, and data storage. Trusted by top semiconductor firms and research universities worldwide. Publicly traded on KOSDAQ. Headquarters in Suwon, Korea, with regional hubs in Santa Clara, Mannheim, Paris, Beijing, Tokyo, Singapore, India, and Mexico City. Visit www.parksystems.com for more information.

Scienta Omicron

Scienta Omicron is a leading innovator in Surface Science and Nanotechnology. At our technology centres in Uppsala, Sweden and Taunusstein, Germany we develop and produce high-tech instruments. Our instruments support top researchers globally and are serviced by our regional hubs. We provide state of the art instruments in Electron Spectroscopy, Scanning Probe Microscopy and Thin Film Deposition. Focusing on the race for new unique materials and solutions, in areas like smarter batteries, next generation electronics, quantum technologies, solar energy, intelligent sensors and advanced materials, Scienta Omicron enables development of tomorrow´s materials.

UNISOKU aims to contribute not only to the development of science and technology but also to convenient and affluent society, by responding to our customers’ inquisitive spirit with desire to ‘Observe’, ‘Know’ and ‘Solve’ through our measuring system. UNISOKU

Local Information

About Singapore

Beyond the picture-perfect skyline and bustling city centre, there’s so much more for visitors to explore in Singapore. Singapore is a city of not just one but 63 islands. There are 62 offshore islands namely Sentosa (the largest), Pulau Ubin, St John’s Island and the Sisters’ Islands. Our Night Safari provides a nocturnal experience like no other in the city; it is also the world’s very first night zoo. Opened in 1994, the 35-hectare park features over 1,000 animals in their natural nighttime environments. Our first man-made waterfall was built at Jurong Bird Park in 1971, dropping from a height of 30 meters. You will also find the world’s tallest indoor waterfall at 35 meters at the Cloud Forest in Gardens by the Bay. This huge waterfall is the centrepiece of the misty conservatory, designed to house plant life from the tropical highlands. There is also an even taller indoor waterfall, at 40 meters, at Jewel Changi Airport. Singapore Botanic Gardens was inscribed as a UNESCO World Heritage in 2015. The most popular attraction is the National Orchid Garden, which houses thousands of orchid species known as Very Important Plants (VIPs). Over 200 hybrid orchids in this garden have been affectionately named after visiting foreign dignitaries such as Nelson Mandela, the Duke and Duchess of Cambridge as well as celebrities like actors Jackie Chan, Zhou Xun and Bae Yong Jun. There are tons of off-the beaten-track neighbourhoods to explore and for those who are passionate about food, these are where lots of local delicacies by time-tested hawkers to award-winning homegrown chefs meet.

Conference Layout Plan (Level 2) F&B / Exhibition Area

Poster Session

F&B

Legend: 1. Park System (Korea) 2. ARC Science 3. Boson (Beijing) Co Ltd 4. Bruker 5. Scienta Omicron 6. CreTecFischer & Co GmbH 7. HI-TECH Instruments Pte Ltd

Local Information

Conference Activities:

Date

Type of Activity

Time

Information

25 th September

Welcome Reception

5.40pm onwards

Evening cocktail and refreshments will be provided at Level 2 , UTown (at the F&B / Exhibition area) Hop on a 30 minutes bumboat tour at the starting point – the Clarke Quay Jetty. Cruising along the Boat Quay stretch, you’ll be able to admire a cityscape that’s a study in contrasts, and testament to Singapore’s unique culture—the soaring skyscrapers of the Central Business District (CBD), towering over traditional shophouses that have been given a new lease on life. The district comes alive at dusk and its picturesque shophouses are certainly make for great photo opportunities. Buses will be provided from Park Ave Rochester Hotel starting from 4.00pm onwards* Please refer to the shuttle bus schedule on page 08 A localized Live Seafood restaurant with 100 kinds of fresh seafood to taste. We will also be having our Poster Prize Presentation during the banquet dinner. Buses will be provided from Clarke Quay to the dinner venue after the excursion . Please refer to the shuttle bus schedule on page 08

28 th September

Excursion-Singapore Bumboat River Cruise

5.00pm onwards

Location : Bumboat Ticketing Counter

Located at Clarke Quay Jetty (Beside Hooters Restaurant) 3D River Valley Rd, #01-03 Block D, Singapore 179023

Conference Banquet Dinner

28 th September

6.45pm onwards

Location : Ah Yat Seafood Restaurant 200 Turf Club Rd, #03 - 01 / 02, Singapore 287994

Local Information

Daily Shuttle Bus Schedule:

Time

Day

From

0800

25/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0830

25/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0800

26/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0830

26/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0800

27/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0830

27/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0800

28/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

0830

28/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

1520 / 1540

28/09

U-TOWN

PARK AVE ROCHESTER HOTEL

1615

28/09

PARK AVE ROCHESTER HOTEL

CLARKE QUAY

Drop off along River Valley Road

1745

28/09

CLARKE QUAY

TURF CITY AH YAT SEAFOOD RESTAURANT

2200

28/09

TURF CITY AH YAT SEAFOOD RESTAURANT

PARK AVE ROCHESTER HOTEL

0815

29/09

PARK AVE ROCHESTER HOTEL

U-TOWN

Drop off at Stephen Raidy Centre 2 College Ave West Singapore 138607

Oral Session

Oral Session- Session 1 25 th September 2023 (Monday) @ Auditorium

Session Chair : Xiaohui Qiu

Comprehensive Single-Molecular Characterization of Cobalt Phthalocyanine Molecules on Ag(111) for Surface Catalysis Applications

1100 HRS

OR-03-005

Prof Udo Schwarz Yale University

Local Probe Isomerization in a One-Dimensional Molecular Array

1120 HRS

OR-05-063

Asst Prof Shigeki Kawai National Institute for Materials

On-surface synthesis of nonplanar graphene nanoribbons embedded with periodic divacancies

1140 HRS

OR-03-019

Prof Chuanxu Ma University of Science and Technology of China

Regulating Reaction Pathways In Coordinated Chains By The Direction of Mechanical Forces

1200 HRS

OR-05-091

Dr Xin Li Peking University

Monday 1100 - 1120

COMPREHENSIVE SINGLE-MOLECULAR CHARACTERIZATION OF COBALT PHTHALOCYANINE MOLECULES ON Ag(111) FOR SURFACE CATALYSIS APPLICATIONS

Xinzhe Wang ,1 Percy Zahl ,2 Hailiang Wang, 3 Eric Altman, 1 and Udo D. Schwarz 1,3*

1 Dept. of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06511, USA. 2 Brookhaven National Lab, Upton, NY 11973, USA. 3 Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06511, USA. Email: udo.schwarz@yale.edu

Recently, Wang et al. [1,2] have found a promising class of hybrid catalysts based on cobalt phthalocyanines (CoPcs) immobilized on carbon nanotube supports that promote the methanol production from CO2. Thereby, the binding strength of the intermediate CO to the cobalt atom at the center of the CoPcs catalyst molecule has been recognized as a key descriptor affecting catalytic efficiency, with the ideal CO-Co binding strength being neither too strong nor too weak. To study this problem systematically at the single molecule level, we present a comprehensive, three-dimensional examination of CoPc molecules on Ag(111) using low-temperature, ultrahigh vacuum scanning probe microscopy (SPM). Scanning tunneling microscopy, noncontact atomic force microscopy, 3D-SPM, and Kelvin probe force microscopy techniques were carried out to characterize the CoPc molecule. We successfully identified the geometric structure (panel a of the figure below), electron distribution, and local barrier height of a single CoPc molecule. The equilibrium distances and potential energies at equilibrium distances (panel c) were also calculated across the molecule based on the 3D-SPM we preformed (panel b). A particularly noteworthy aspect of the approach is that after characterizing the molecule, systematically changing the substituents/side chains of the CoPc or the substrate the CoPc molecules sit on will during future experimentation allow to clarify the effect of these changes on the CO-Co binding strength and eventually enable a fine tuning of the binding strength, which may open new avenues to optimize the catalytic reaction.

Fig. (a) NC-AFM image of CoPc with the structural model overlayed. At each pixel, F(z) curves were acquired. (b) Four F(z) curves obtained at the locations indicated in (a) demonstrate the ability to examine tip-sample interactions locally with high resolution using 3D-SPM; note that the contribution of the substrate to the tip-sample interaction has been removed from the data. Since the tip is terminated with a CO molecule, these curves mainly reflect the force between the CO and the CoPc. (c) By fitting the extracted force curves at each pixel, maps of the energy minima for the CO-CoPc interactions can be recovered, which allow conclusions on the location-dependent adhesion of CO to the CoPc.

References [1] Y. Wu, Z. Jiang, X. Lu, Y. Liang, and H. Wang, Nature, 2019, 575, 639. [2] X. Zhang et al., Nature Communications, 2017, 8, 14675.

Monday 1120 - 1140

Shigeki Kawai* 1,2 , Orlando J. Silveira 3 , Lauri Kurki 3 , Zhangyu Yuan 1,2 , Tomohiko Nishiuchi 4,5 , Takuya Kodama 4,5, Kewei Sun 1 , Oscar Custance 1 , Jose L. Lado 3 , Takashi Kubo 4,5 , Adam S. Foster 3,6 1 Center for Basic Research on Materials, National Institute for Materials, Tsukuba, Ibaraki 305-0047, Japan 2 Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan 3 Department of Applied Physics, Aalto University, 00076 Aalto, Helsinki, Finland 4 Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan. 5 Innovative Catalysis Science Division (ICS), Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka, 565-0871, Japan. 6 WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa 920-1192, Japan Email: KAWAI.Shigeki@nims.go.jp LOCAL PROBE ISOMERIZATION IN A ONE DIMENSIONAL MOLECULAR ARRAY On-surface chemical synthesis has attracted tremendous interest of researchers.[1] Particularly, combining with bond-resolved scanning probe microscopy,[2] this field has been rapidly developed. The structure of the small molecule is first identified by scanning, and then is modified by tunneling current/force. The product is finally identified by scanning again,[3] that is, local probe chemical reaction. Here, we present synthesis and characterization of dehydroazulene isomer and diradical units in three-dimensional organometallic compounds on Ag(111) with a combination of low-temperature scanning probe microscopy and density functional theory calculations.[4] Tip-induced voltage pulses firstly result in the formation of a diradical species via successive homolytic fission of two C-Br bonds in the naphthyl groups, which are subsequently transformed to chiral dehydroazulene moieties. The delicate balance of the reaction rates among the diradical and two stereoisomers, arising from an in-line configuration of tip and molecular unit, allows directional azulene-to-azulene and azulene-to-diradical local probe isomerization in a controlled manner.

Fig. Systematic local probe isomerization of azulene unit on 3D-OMC. “Nanoprobe GRP. NIMS©” in 8-bit binary ascii code is embedded via sequential 71 isomerization in the dehydroazulene array.

References [1] S. Clair, D. G. de Oteyza, Chem. Rev. 119, 4717 (2019). [2] Gross, F. Mohn, N. Moll, P. Lilkeroth, G. Meyer, Science 325, 1110 (2009) [3] F. Albrecht, S. Fatayer, I. Pozo, I. Tavernelli, J. Reep, D. Peña, L. Gross. Science 118, 298 (2022) [4] S. Kawai et al (to be submitted)

Monday 1140 - 1200

ON SURFACE SYNTHESIS OF NONPLANAR GRAPHENE NANORIBBONS EMBEDDED WITH PERIODIC DIVACANCIES

Chuanxu Ma 1,* , Ruoting Yin 1 , Zhengya Wang 1 , Jie Meng 1 , Jianing Wang 1 , Zhen-Lin Qiu 2 , Yuan-Zhi Tan 2 , Qunxiang Li 1 , Bing Wang 1* 1 Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China 2 Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, China Email: cxma85@ustc.edu.cn; bwang@ustc.edu.cn

Periodically embedding structural defects, such as vacancies, nonhexagonal rings, and heteroatoms into the basal hexagonal lattice of graphene provides a predicable way aiming to electronic properties engineering for potential applications. Recent development of on-surface synthesis [1], based on rationally designed molecular precursors, has become a remarkable success in atomically precisely fabricating novel graphene superlattices with periodic structural modulations, as exemplified by nanopores in graphene sheets and graphene nanoribbons (GNRs) [2-4], and heteroatoms of B and N in GNRs [5,6], and also a wide range of interesting carbon allotropes that consist of various nonbenzenoid combinations [7-10]. However, it still remains challenging to synthesize periodic divacancies embedded GNRs. In this talk, I will introduce two different approaches toward this goal. One is the substrate-step assisted synthesis of the eight-carbon-wide armchair GNRs embedded with periodic hydrogenated divacancies [11]. The other is the self-limited embedding of alternating 585-ringed divacancies and metal atoms into graphene nanoribbons with width of seven carbon atoms [12]. We perform high-resolution scanning tunneling microscopy/spectroscopy and non-contact atomic force microscopy joint with first-principles calculations, we in situ monitor the evolution of the distinct structural and electronic properties in the reaction intermediates. We observe distinct nonplanar features and electronic properties of the hydrogenated and 585-ringed divacancies. The reaction mechanisms are further elucidated by our nudged elastic band calculations, which unveil the important roles of the substrate heterogeneities. Our findings open an avenue to introducing periodic impurities of divacancy pores, single metal atoms and nonhexagonal rings in on-surface synthesis, which may provide a novel route for multifunctional graphene nanostructures. [2] P. H. Jacobse et al., J. Am. Chem. Soc. 142, 13507 (2020). [3] R. Pawlak et al., J. Am. Chem. Soc. 142, 12568 (2020). [4] C. Moreno et al., Science 360, 199 (2018). [5] E. C. H. Wen, P. H. Jacobse, J. Jiang, Z. Wang, R. D. McCurdy, S. G. Louie, M. F. Crommie, and F. R. Fischer, J. Am. Chem. Soc. 144, 13696 (2022). [6] S. Kawai, S. Saito, S. Osumi, S. Yamaguchi, A. S. Foster, P. Spijker, and E. Meyer, Nat. Commun. 6, 8098 (2015). [7] Q. Fan et al., Science 372, 852 (2021). [8] B. de la Torre et al., Nat. Commun. 11, 4567 (2020). [9] M. Di Giovannantonio, Q. Chen, J. I. Urgel, P. Ruffieux, C. A. Pignedoli, K. Mullen, A. Narita, and R. Fasel, J. Am. Chem. Soc. 142, 12925 (2020). References [1] H. Wang, H. S. Wang, C. Ma, L. Chen, C. Jiang, C. Chen, X. Xie, A.-P. Li, and X. Wang, Nat. Rev. Phys. 3, 791 (2021).

[10] D.-Y. Li et al., J. Am. Chem. Soc. 143, 12955 (2021). [11] R. Yin et al., J. Am. Chem. Soc. 144, 14798 (2022). [12] Z. Wang et al., J. Am. Chem. Soc., doi:10.1021/jacs.3c00111 (2023).

Monday 1200-1220

REGULATING REACTION PATHWAYS IN COORDINATED CHAINS BY THE DIRECTION OF MECHANICAL FORCES

Xin Li, Zhen Xu, Jie Li, Yajie Zhang, Yongfeng Wang*

School of Electronics, Peking University, 100871 China Email: yongfengwang@pku.edu.cn

Manipulation at atomic and molecular scales has been achieved widely with a scanning tunneling microscope (STM) or atom force microscope (AFM), which contributes to the development of functional nanoscale devices. The manipulation can be achieved in various ways such as the electrical field, the stimulation of the tunneling electrons, or the interaction forces between tip and sample. In our previous work, we have achieved the manipulation of the spin state in the coordinated chains, where the Ni atoms coordinated by deprotonated tetrahydroxybenzene linkers on Au(111) are at a low-spin (S = 0) or a high-spin (S = 1) state alternately along the chains. Here, we use Au and C60 tips to realize reversible manipulation of the above-mentioned Ni atoms. Combining the STM, AFM, and density functional theory (DFT) calculations, we find that the Au (C60) tip could pull (push) the Ni atoms, and induce the transition from high-spin (low-spin) to low-spin (high-spin) state by attractive (repulsive) force. During the manipulation, the collective switching of multiple Ni atoms can be restricted in a single chain, suggesting that the manipulation by mechanical force is more localized than the stimulation of electrons. These findings provide more possibilities for the application of mechanochemistry in multifunctional spintronics.

Fig. Schematics of an Au tip pulling the Ni atom from high-spin state into low-spin state by attractive force (left), and a C60 tip pushing the Ni atom from low-spin state into high-spin state by repulsive force (right). Color code: gray, C; white, H; red, O; gray-blue, Ni; yellow, Au.

References [1] Jing Liu, Yifan Gao, Tong Wang, Qiang Xue, Muqing Hua, Yongfeng Wang, Li Huang, and Nian Lin ACS Nano 2020 14, 9

Oral Session

Oral Session- Session 2 25 th September 2023 (Monday) @ Auditorium

Session Chair : Lu Jiong

The Nature of a Chemical Bond Influences Sliding Friction at the Atomic Scale

1400 HRS

OR-10-013

Dr Alfred John Weymouth University of Regensburg

Moiré-Tile -Tile Manipulation-Induced Friction Switch of Graphene on a Platinum Surface

1420 HRS

OR-10-073

Dr J.G. Vilhena Universidad Autónoma de Madrid

Dr Chengfu Ma University of Science and Technology of China Atomic force microscopy manipulation and friction measurement of nanoscale droplets confined by two-dimensional sheets

1440 HRS

OR-10-007

Exploring in-plane interactions beside an adsorbed molecule with lateral force microscopy

1500 HRS

OR-10-016

Ms Shinjae Nam University of Regensburg

Spatially Resolved Interfacial Polarization Timescales At The Si/SiO2 Surface

1520 HRS

OR-10-071

Ms Megan Cowie McGill University

Monday 1400 - 1420

THE NATURE OF A CHEMICAL BOND INFLUENCES SLIDING FRICTION AT THE ATOMIC SCALE

Alfred J. Weymouth 1 , O. Gretz 1 , S. Nam 1 , L. Hörmann 2 , O.T. Hofmann 2 , F.J. Giessibl 1

1 Faculty of Physics, University of Regensburg; Regensburg, 93053, Germany 2 Institute of Solid State Physics, Graz University of Technology; Graz, 8010, Austria.

Email: jay.weymouth@ur.de

We perform lateral force microscopy (LFM), a technique in which the AFM sensor is mounted so that the tip oscillates laterally over a surface [1]. Using techniques established in FM-AFM, we can evaluate both the conservative and dissipative interactions with the surface. We can also functionalize our tip with a single CO molecule for a well-defined and inert tip termination [2]. Previously, we discovered that we could directly measure the energy loss as we pull our tip – an asperity ending in a well-controlled single atom – over a single chemical bond [3,4]. In this contribution, we address the question of whether the nature of the chemical bond has a direct impact on sliding friction. We find that friction is indeed higher over a covalent bond compared to a hydrogen bond.

Fig. a) The frequency shift, f, is a measure of the conservative force interaction and allows us to determine the position of each surface atom. b) The energy loss is higher over chemical bonds that are perpendicular to the direction of the tip oscillation (horizontal). c) We interpret this energy loss as being a result of the flexible apex snapping over a chemical bond.

References [1] F. J. Giessibl, M. Herz, and J. Mannhart, Proc. Natl. Acad. Sci., 2002, 99, 12006. [2] L. Gross, F. Mohn, N. Moll, P. Liljeroth, and G. Meyer, Science, 2009, 325, 1110. [3] A. J. Weymouth, E. Riegel, O. Gretz, and F. J. Giessibl, Phys. Rev. Lett., 2020, 124, 196101. [4] A. J. Weymouth, O. Gretz, E. Riegel, and F. J. Giessibl, Jpn. J. Appl. Phys., 2022, 61, SL0801.

Monday 1420 - 1440

MOIRÉ TILE MANIPULATION INDUCED FRICTION SWITCH OF GRAPHENE ON A PLATINUM SURFACE

J.G. Vilhena * 1,2,3 , A. Zhao Liu* 3,4 , Antoine Hinaut 3 , Sebastian Scherb 3 , Feng Luo 4 , Junyan Zhang 5 , Thilo Glatzel 3 , Enrico Gnecco 6 , and Ernst Meyer* 3 1 Dep. de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain 2 IFIMAC - Condensed Matter Physics Center, Universidad Autónoma de Madrid, E-28049 Madrid, Spain 3 Department of Physics, University of Basel, 4056 Basel, Switzerland; 4 Tianjin Key Lab for Rare Earth Materials and Applications, Nankai University, 300350 Tianjin, China 5 State Key Laboratory of Solid Lubrication, Chinese Academy of Sciences, 730000 Lanzhou, China 6 Smoluchowksi Institute of Physics, Jagiellonian University in Krakow, 30-348 Krakow, Poland Email: guilherme.vilhena@uam.es

Friction control and technological advancement are intimately intertwined. Concomitantly, two-dimensional materials occupy a unique position for realizing quasi-frictionless contacts. However, the question arises of how to tune superlubric sliding. Drawing inspiration from twistronics, we propose to control superlubricity via moiré patterning. Friction force microscopy and molecular dynamics simulations unequivocally demonstrate a transition from a superlubric to dissipative sliding regime for different twist angles of graphene moirés on a Pt(111) surface triggered by the normal force. This follows from a novel mechanism at superlattice level where, beyond a critical load, moiré tiles are manipulated in a highly dissipative shear process connected to the twist angle. Importantly, the atomic detail of the dissipation associated with the moiré tile manipulation - i.e., enduring forced registry beyond a critical normal load-allows the bridging of disparate sliding regimes in a reversible manner, thus paving the road for a subtly intrinsic control of superlubricity.

Fig. Moiré tile nano-manipulation: switching off/on superlubricity.

References [1] A. Zhao Liu*, J.G. Vilhena*, Antoine Hinaut, Sebastian Scherb, Feng Luo, Junyan Zhang, Thilo Glatzel, Enrico Gnecco, and Ernst Meyer*, Nano letters, 2023 , asap. (https://pubs.acs.org/doi/10.1021/acs.nanolett.2c03818)

Monday 1440 - 1500

ATOMIC FORCE MICROSCOPY MANIPULATION AND FRICTION MEASUREMENT OF NANOSCALE DROPLETS CONFINED BY TWO-DIMENSIONAL SHEETS

Chengfu Ma*, Yuhang Chen, Jiaru Chu

1 Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China Email: chfuma@ustc.edu.cn

Pinning of droplets on solids is an omnipresent phenomenon in nature and in daily life that attracts intense research interest. Understanding the pinning behaviors of droplets is not only academically important but also key for many industrial applications such as self-cleaning surfaces, oil/water separation, and directional liquid transport. Here, we investigate the pinning behaviors of nanoscale droplets that are confined by a two-dimensional (2D) elastic sheet onto a substrate by using atomic force microscopy (AFM). The protection provided by the 2D elastic sheet to the droplets makes manipulating them and measuring their pinning forces by an AFM probe possible. This brings the study of the pinning effect of wetting into the micro- and nanometer scales. Our results reveal a time-dependent pinning effect of the confined nanodroplets. The droplets’ lateral retention forces are found to increase with increasing their resting times until saturations. Our analysis suggests that dissipation by fine deformations of the substrate, induced by vertical tensions at the contact lines, plays important roles in the droplet’s pinning. The creep of the deformation is suggested to result in the time dependence of the droplet’s pinning as well as the observed residual ridge structures left by droplets at their original contact lines after their spreads after long resting times.

Acknowledgements We thank the support from the National Natural Science Foundation of China (No. 52005476).

References [1] C. Ma, Y. Chen, and J. Chu. Time-dependent pinning of nanoblisters confined by two-dimensional sheets. Part 1: scaling law and hydrostatic pressure. Langmuir, 39(2), 701-708 (2023). [2] C. Ma, Y. Chen, and J. Chu. Time-dependent pinning of nanoblisters confined by two-dimensional sheets. Part 2: contact line pinning. Langmuir, 39(2), 709-716 (2023).

Monday 1500 - 1520

EXPLORING IN PLANE INTERACTIONS BESIDE AN ADSORBED MOLECULE WITH LATERAL FORCE MICROSCOPY

Shinjae Nam 1 , Elisabeth Riegel 1 , Oliver Gretz 1 , Lukas Hörmann 2 , Oliver T. Hofmann 2 , Alfred J. Weymouth 1* , and Franz J. Giessibl 1 1 Faculty of Physics, University of Regensburg, 93053 Regensburg, Germany 2 Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria

Email: Shinjae.Nam@physik.uni-regensburg.de

One of the most important phenomena that hydrogen atoms take part in is hydrogen bonding. Many efforts have been made to directly observe hydrogen atoms, including by AFM [1], but it is an ongoing challenge to directly observe them in planar molecules. We use frequency modulation lateral force microscopy (LFM) [2], where the tip is oscillated laterally to directly measure short-range forces. We approached the side of the PTCDA molecule with a CO terminated tip [3] and found that we could directly observe the hydrogen atoms. One advantage of PTCDA is that it offers both H-terminated and O-terminated sides. Interestingly we did not observe a signature of hydrogen bonding between PTCDA and the CO at the tip apex. We explain our observations by including the electrostatic interaction of the large dipole of the metal apex via density functional theory calculations of the electrostatic field above the molecule.

Fig. Experimental observations of PTCDA on Cu(111). (a) Constant height Δf (LFM) image of the side of a PTCDA island probed with CO-terminated tip. Ball and stick models of two PTCDA molecules are shown with oxygen (red), hydrogen (white), and carbon (grey) atoms. The schematic figure of the tip heights is shown in (b). Force maps at the H-side and at the O-side (c) at z = 600 pm and (d) at z = 460 pm. References [1] S. Kawai, T. Nishiuchi, T. Kodama, P. Spijker, R. Pawlak, T. Meier, J. Tracey, T. Kubo, E. Meyer, A. S. Foster, Sci. Adv. 2017, 3, e1603258

[2] F.J. Giessibl, M. Herz, J. Mannhart, Proc. Natl. Acad. Sci. 2002, 99, 12006. [3] L. Gross, F. Mohn, N. Moll, P. Liljeroth, G. Meyer, Science, 2009, 325, 1110.

Monday 1520-1540

SPATIALLY RESOLVED INTERFACIAL POLARIZATION TIMESCALES AT THE Si/SiO 2 SURFACE

Megan Cowie and Peter Grütter

1 Department of Physics, McGill University, Montrèal, Canada Email: megan.cowie@mail.mcgill.ca

When a time-varying electric field is applied to a semiconductor, charge reorganization at the semiconductor surface leads to dielectric dispersion. In fm-AFM experiments, charge reorganization occurs over every oscillation cycle due to changes in band bending as the tip-sample separation varies. This is a dispersive process, and consequently (for charge reorganization timescales much faster than the oscillation period) manifests as an increase in the fm-AFM drive/excitation amplitude. In this work, we measure surface charge organization timescales on the order of nanoseconds to tens of nanoseconds at the Si/SiO 2 surface using a 300 kHz cantilever in UHV at room temperature. The timescale of charge organization depends on the applied gate bias, and can be directly correlated to the characteristic surface charge distribution that occurs in each bias regime of a metal (tip) – insulator (vacuum) – semiconductor (sample) MIS capacitor. Isolated trap states at the surface additionally influence this charge reorganization timescale: At biases where there is significant interaction between the semiconductor surface charge density and the isolated trap state, the charge reorganization timescale increases. This leads to an increase in the fm-AFM drive/excitation amplitude, which peaks at a bias corresponding to the position of the trap state within the surface band gap as well as its spatial depth within the Si/SiO 2 interface. This bias-dependent spatially localized peak manifests as a ring when the surface is measured at constant tip-sample separation at large biases, as shown in Figure 1. These measurements are particularly significant for the advancement of semiconductor qubits, as the stability and robustness of buried qubits depends on the uniformity of the dielectric dispersion within the semiconducting electronic bath.

Fig. 1 Multipass fm-AFM drive/excitation measurements of trap states at the Si/SiO 2 surface at variable bias at room temperature. Two different trap states are shown: A-C (negative biases) and D-F (positive biases). These images indicate a bias-dependent spatially localized trap-induced increase in the dielectric dispersion (or charge reorganization timescale) at the surface. The lateral scale bar is 30 nm, and the vertical scale bar for A-F is 0:550 meV /cycle (0:~0.09 aJ/cycle).

Oral Session

Oral Session- Session 3 25 th September 2023 (Monday) @ Auditorium

Session Chair: Shijing Tan

Scanning Ion Conductance Microscopy (SICM) for Biological and Material Science Applications

1620 HRS

OR-01-102

Dr Petr Gorelkin ICAPPIC Limited

Frequency and Damping Noise of Atomic Force Microscopy Cantilevers with Optomechanically Modified Quality Factor at Low Temperature

1640 HRS

OR-01-083

Dr Yoichi Miyahara Texas State University

Characterization of Hydrogen Resist Lithography Quantum Dots using AFM

1700 HRS

OR-01-070

Mr Jose Bustamante Physics Department, McGill University

Using Single-Electron Force Microscopy to Determine Enzymatic Electron Transfer Dynamics

1720 HRS

OR-01-072

Ms Catherine Boisvert McGill University

Monday 1620 - 1640

SCANNNG ION CONDUCTANCE MICROSCOPY (SICM) FOR BIOLOGICAL AND MATERIAL SCIENCE APPLICATIONS

Petr Gorelkin 1,2 , Alexander Erofeev 1,2, Vasilii Kolmogorov 2 , Pavel Novak 1,3 , Andrew Shevchuk 1,3 , Christopher Edwards 1,3 , Yuri Korchev 1,3 1 ICAPPIC Limited, The Fisheries, Mentmore Terrace, London, E8 3PN, United Kingdom 2 National University of Science and Technology “MISiS”, Moscow, Russia Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom Email: pg@icappic.com

The SICM probe a nanopipette is ideally suited for performing nanoscale assays on the cell surface. These include patch-clamp recording from individual surface structures, iontophoretic delivery of reagents, or pressure micro-application via the pipette to probe mechanical properties of the cell or to deliver reagents. Until now, these advantages of SICM have never been fully explored in such important preparations as brain slices or cell cultures with a complex surface topology because the requirement for a relatively flat specimen surface has been intrinsic to standard scanning probe techniques. We can clearly resolve fine dendritic segments, even those “suspended” in space [1]. In order to unambiguously identify synaptic connections, we combined this new imaging mode with fluorescence and nanomechanical imaging [2]. We observed how the mechanical properties of single cells changed in the presence of drugs acting on a cytoskeleton [3]. We observed how the mechanical properties of single cells changed in the presence of drugs acting on various parts of the cytoskeleton. We have also shown the possibility of applying low-stress SICM for long-term nanomechanical mapping in real-time and the visualization of the dynamic process related to the changes in the mechanical properties of the living cells. This technology is fast enough to observe relatively rapid biological events. We have successfully combined scanning nanopipettes with principles of electrophysiology, fluorescence microscopy, electrochemistry, electrophoresis, and electroosmosis to investigate single channels and receptors in cellular membranes, to deliver biomolecules to precisely defined locations in cell cultures, and to perform single cell analysis [4]. Also, we have demonstrated applications of scanning ion conductance microscopy for nanoscale activity mapping of electrodes for ion batteries and investigating of nanoscale electrochemical properties of novel materials. With recent progress in nanopore-based biosensing and sequencing, and nanopipette-based 3D printing we are only just beginning to open a new window into the life at nanoscale and realizing new possibilities for engineering of interfaces between single cells and man-made electronics for therapeutic and diagnostic purposes or synthesis of entirely novel bioelectrical circuits and materials.

References [1] P. Novak et al., Nature Methods., 6(4), 279-81 (2009) [2] V.S. Kolmogorov et al., Nanoscale, 13, 6558-6568 (2021) [3] A.E. Machulkin et al., J. Med. Chem. 64, 23, 17123–17145, (2021) [4] Y. Zhang et al., Nature Communications, 10, 5610 (2019)

Monday 1640 - 1700

FREQUENCY AND DAMPING NOISE OF ATOMIC FORCE MICROSCOPY CANTILEVERS WITH OPTOMECHANICALLY MODIFIED QUALITY FACTOR AT LOW TEMPERATURE

Noah Austin-Bingamon 1 , Binod DC 2 , and Yoichi Miyahara 1,2*

1 Department of Physics, Texas State University, San Marcos, Texas 78666, USA 2 Materials Science, Engineering and Commercialization program, Texas State University Email: yoichi.miyahara@txstate.edu

Noise in the frequency and the damping signals are key parameters in determining microscope performance in frequency modulation atomic force microscopy (FM-AFM). We present a study of noise in the frequency and damping signals of AFM cantilevers used in a low temperature FM-AFM system with fiber-optic interferometric sensing of the cantilever deflection. Due to an optomechanical coupling between cantilever oscillation and the optical field, the quality (Q) factor and resonant frequency are both dependent on the optical cavity length (fiber-cantilever gap distance) [1,2]. We use an optical setup with two infrared lasers (1550nm and 1310nm), each of which is used for detection and excitation of the cantilever oscillation. While the intensity of the 1310nm laser (excitation laser) is modulated to excite the cantilever oscillation via optical force [3], varying the mean intensity of the excitation laser can change the effective Q factor, allowing us to compare the frequency and damping noises with the same detection sensitivity. An automated protocol was developed to scan the fiber-cantilever distance and measure the effective Q factor, resonant frequency, and frequency noise at each distance. A digital phase-locked loop was used to drive the cantilever oscillation and measure the frequency and Q. The fiber position was scanned using a computer-controlled piezoelectric stick-slip motor. Figure 1 shows (a) thermal noise spectra of a Pt coated cantilever (f0 = 145 kHz, k = 20 N/m), (b) time trace of frequency shift with four different effective Q factors ranging from 588k to 61k. The measurement temperature is 3.5 K. This result shows that the frequency shift noise decreases with increasing effective Q factor that is modified by optomechanical effect. Similarly, we have observed the decreasing damping noise with increase effective Q factor. We will present the details of the experiment and discuss the mechanism of the noise reduction and the implication of the results on FM-AFM measurements. We gratefully acknowledge funding from NSF-PREM (DMR-2122041), NSF-CAREER (DMR-2044920) and NSF-MRI (DMR-2117438). This work is also supported by Texas State University.

Fig. 1 (a) Thermal spectra of the cantilever. Each curve is shifted vertically by 10-2 for clarity. (b) Time trace of frequency shift noise. Each curve is shifted vertically by 1 Hz for clarity. In (a) and (b), the effective quality factor of green, blue, pink and black traces are 588k, 120k, 77k, and 62k, respectively.

References [1] C. H. Metzger and Kh Karrai, Nature 2004, 432 , 1002. [1] H. Hoelscher, et al., Appl. Phys. Lett. 2009, 94 , 223514. [2] Y. Miyahara, EPJ Tech. Instrum. 2020, 7 , 2.

Monday 1700 - 1720

CHARACTERIZATION OF HYDROGEN RESIST LITHOGRAPHY QUANTUM DOTS USING AFM

Jose Bustamante 1,3 , Kieran Spruce 2 , Taylor Stock 2 , Yoichi Miyahara 4 , Logan Fairgrieve-Park 1 , Catherine Boisvert 1 , Neil Curson 2 , Peter Grutter 1 * 1 De1 Physics Department, McGill University, Montreal, H3A 2T8, Canada 2 London Centre for Nanotechnology, University College London, London WC1H 0AH, U.K. 3 Departamento de Física, Universidad San Francisco de Quito, Quito 170901, Ecuador 4 Department of Physics, Texas State University, San Marcos, Texas 78666 USA Email: jose.bustamante3@mail.mcgill.ca

Single dopant atoms in silicon are promising candidates for qubit hosts for the implementation of quantum computing. The plethora of methods for fabrication of silicon semiconductor devices offers an attractive platform for the development of quantum technologies. Hydrogen Resist Lithography is a technique that enables the positioning of single dopant atoms of Phosphorus or Arsenic with atomic resolution on a silicon crystal, which is then encapsulated by a silicon crystalline layer for protection [1]. This process can be used to fabricate Quantum Dots (QD) and electrodes over the surface of a silicon crystal with ultimate lateral resolution. Conveniently, Atomically defined QDs or single dopant atoms then arise as candidates for hosts of charge or spin qubits. So far, these devices have been characterized with transport measurements, and RF reflectometry [3]. However, AFM offers an interesting alternative to characterize these devices using an AFM tip both as a probe to acquire topography and other material properties, and as an electric movable gate to manipulate the electrostatic environment of the QD. EFM can also measure the energy levels of QDs and study the coupling between two QDs [2]. We have built an AFM capable of finding the relevant nanometre size structure in a macroscopic chip, imaging buried structures of dopant atoms, and detecting single electron tunnelling events to QDs. I will present the instrument and discuss preliminary results in finding and characterizing hydrogen resist lithography devices.

Fig. Single electron transistor made of a single Hydrogen Resist Lithography QD. Center: STM image of the device before encapsulation showing the QD, source, drain and two Gates, taken in London. Outer image: NC-AFM image of the metal connections (two per stm defined contact) taken at Montréal.

References [1]T. Stock et al. , ACS Nano 14,3, 3316–3327 (2020).

[2]Y. Miyahara, A. Roy-Gobeil and P. Grutter, Nanotechnology 28, 064001 (2017). [3]X. Jehl, Y. Niquet and M. Sanquer, J. Phys.: Condens. Matter 28, 10 (2016).

Monday 1720-1740

USING SINGLE-ELECTRON FORCE MICROSCOPY TO DETERMINE ENZYMATIC ELECTRON TRANSFER DYNAMICS

Catherine Boisvert 1 , José Bustamante 1 , Logan Fairgrieve-Park 1 , Ons Hmam 2 , Antonella Badia 2 , Peter Grütter 1

1 Department of Physics, McGill University, 3600 rue University, Montréal, Québec H3A 2T8, Canada 2 Department of Chemistry, Université de Montréal, 1375 avenue Thérèse-Lavoie-Roux, Montréal, Québec H2V 0B3, Canada Email : catherine.boisvert4@mail.mcgill.ca Enzymes have been of great interest due to their fascinating, yet complex redox properties and their use in green energy production. Specifically, metalloenzymes have great potential in clean H2 utilization and CO2 reduction by means of carbon scrubbing [1]. It is thus imperative to understand the structural properties of metalloenzymes and their internal redox and electron transfer rates, since these quantum properties underpin catalytic activity. To do so, we can use single-electron electrostatic force microscopy (e-EFM), where an oscillating conductive cantilever induces electron tunneling events in structures with discrete electronic states. In this AFM technique, we monitor the frequency shift and dissipation of the cantilever to determine quantum dot density of states, measure single-electron tunneling rates, and observe transitions between quantized nuclear vibronic states at the single-molecule level [2-4]. With these recent quantum imaging developments in AFM, our low-temperature atomic force microscope (LT-AFM) can be used to image single-electron transfers in single- and multi-redox site metalloenzymes. These single-electron transfer events occur between a gold electrode and the metalloenzyme, and the direct electrical connectivity of the system is enabled by using a self-assembled monolayer attached to a suitable-sized functionalized gold cluster that can be coupled to the metal center of the protein pocket [5]. Details surrounding this sample preparation and the various characterization steps will be presented. Moreover, e-EFM on metalloenzymes can be used to determine Franck-Condon factors associated with redox transitions, measure energetic offsets, and map electronic coupling between redox centers [4,6]. This will therefore allow us to understand and engineer the catalytic activity of metalloenzymes in an effort to develop inorganic biomimetic analogues as sustainable energy solutions [1].

Fig. Frequency shift as a function of bias spectroscopy (Ferrocene molecule). Vibronic energy and tunnelling rate can be extracted from the derivative of the frequency shift response [2].

References [1] B.-E. Jugder, J. Welch, K.-F. Aguey-Zinsou, C. P. Marquis, RSC Advances, 2013, 3 , 8142-2013. [2] A. Roy-Gobeil, Y. Miyahara, K. H. Bevan, P. Grütter, Nano Lett, 2019, 19 , 6104-6108. [3] L. Cockins, Y. Miyahara, S. D. Bennett, A. A. Clerk, S. Studenikin, P. Poole, et al., Proc Natl Acad Sci USA, 2010, 107 , 9496-950. [4] K. H. Bevan, A. Roy-Gobeil, Y. Miyahara, P. Grütter, J Chem Phys, 2018, 149 , 104109. [5] J. M. Abad, M. Gass, A. Bleloch, D.J. Schiffrin, J. Am. Chem. Soc, 2009, 131 , 10229–10236. [6] J. Blumberger, Chem Rev, 2015, 115 , 11191-238.

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