Probing interfacial electronic effects on single‐molecule adsorption geometry and electron transport at atomically‐flat surfaces

The motion of molecular fragments in close contact with atomically flat surfaces is still not fully understood. Does a more favourable interaction imply a larger barrier towards motion even if there are no obvious minima? Here, we use mechanically interlocked rotaxane-type derivatives of SWNTs (MINTs) featuring four different types of macrocycles with significantly different affinities for the SWNT thread as models to study this problem. Using molecular dynamics, we find that there is no direct correlation between the interaction energy of the macrocycle with the SWNT and its ability to move along or around it. Density functional tight-binding calculations reveal small (<2.5 Kcal·mol-1) activation barriers, the height of which correlates with the commensurability of the aromatic moieties in the macrocycle with the SWNT. Our results show that macrocycles in MINTs rotate and translate freely around and along SWNTs at room temperature, with an energetic cost lower than the rotation around the C−C bond in ethane.<br>

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Quantum Algorithm for Simulating Single-Molecule Electron Transport

The Journal of Physical Chemistry Letters ◽

10.1021/acs.jpclett.0c03724 ◽

2021 ◽

Vol 12 (4) ◽

pp. 1256-1261

Author(s):

Soran Jahangiri ◽

Juan Miguel Arrazola ◽

Alain Delgado

Keyword(s):

Electron Transport ◽

Single Molecule ◽

Quantum Algorithm

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Influence of Momentary Annealing on the Nanoscale Surface Morphology of Room Temperature Pulsed Laser Deposited NiO(111) Epitaxial Thin Films on Atomically Stepped Sapphire (0001) Substrates

MRS Proceedings ◽

10.1557/opl.2013.380 ◽

2013 ◽

Vol 1507 ◽

Author(s):

Ryosuke Yamauchi ◽

Geng Tan ◽

Daishi Shiojiri ◽

Nobuo Tsuchimine ◽

Koji Koyama ◽

...

Keyword(s):

Thin Films ◽

Surface Morphology ◽

Room Temperature ◽

Pulsed Laser ◽

Film Surface ◽

Transient State ◽

Epitaxial Thin Films ◽

Flat Surfaces ◽

Surface Nanostructure ◽

Atomically Flat

ABSTRACTWe examined the influence of momentary annealing on the nanoscale surface morphology of NiO(111) epitaxial thin films deposited on atomically stepped sapphire (0001) substrates at room temperature in O2 at 1.3 × 10−3 and 1.3 × 10−6 Pa using a pulsed laser deposition (PLD) technique. The NiO films have atomically flat surfaces (RMS roughness: approximately 0.1–0.2 nm) reflecting the step-and-terrace structures of the substrates, regardless of the O2 deposition pressure. After rapid thermal annealing (RTA) of the NiO(111) epitaxial film deposited at 1.3 × 10−3 Pa O2, a periodic straight nanogroove array related to the atomic steps of the substrate was formed on the film surface for 60 s. In contrast, the fabrication of a transient state in the nanogroove array formation was achieved with RTA of less than 1 s. However, when the O2 atmosphere during PLD was 1.3 × 10−6 Pa, random crystal growth was observed and resulted in a disordered rough surface nanostructure after RTA.

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Homo- and Hetero-Epitaxial Gallium Nitride Grown by Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-537-g4.11 ◽

1998 ◽

Vol 537 ◽

Author(s):

C.T. Foxon ◽

T.S. Cheng ◽

D. Korakakis ◽

S.V. Novikov ◽

R.P. Campion ◽

...

Keyword(s):

High Temperature ◽

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Defect Density ◽

Boundary Structure ◽

Quantum Well Structures ◽

Flat Surfaces ◽

Grain Boundary Structure ◽

Bulk Gan ◽

Atomically Flat

AbstractVarious methods have been used to initiate growth by Molecular Beam Epitaxy (MBE) of GaN on sapphire, or other substrates, but there is always a problem with morphology and with a high defect density which results in the formation of a sub-grain boundary structure. We show that by using, homo-epitaxial growth on properly prepared bulk GaN substrates, combined with high temperature growth, we obtain a significant improvement in surface morphology. Growth at sufficiently high temperature leads to a rapid smoothing of the surface and to almost atomically flat surfaces over relatively large areas. Multi-Quantum Well structures grown on such GaN epitaxial films are dislocation free with abrupt interfaces.

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A simple surface modification to generate atomically-flat and hydrophobic substrates for gliding assays with protein motors

10.33774/chemrxiv-2021-d62p2-v3 ◽

2021 ◽

Author(s):

Isadonna Tengganu ◽

Neil Karerakattil ◽

Swarup Dey ◽

Devika Kishnan ◽

Rizal Hariadi

Keyword(s):

Single Molecule ◽

Vapor Deposition ◽

Glass Capillary ◽

High Background ◽

Protein Motors ◽

Order Of Magnitude ◽

Protein Motor ◽

Glass Surfaces ◽

Atomically Flat

In vitro gliding assay is a well-established assay for determining the activity of protein motors, such as actin-associated myosins and microtubule-associated kinesins and dyneins. In one of the conventional methods, protein motors are immobilized onto a nitrocellulose-coated coverslip and it propels actin filaments in the presence of ATP. Gliding assays also serve as the foundation for protein-motor-based nanotechnological devices such as biosensing and sorting. However, the preparation of nitrocellulose-coated coverslips is time-consuming and produces rough surfaces. Furthermore, the nitrocellulose film exhibits high background autofluorescence, which can be a problem in single-molecule measurements. Here, we investigated the use of hexamethyldisilazane (HMDS) to study actomyosin function and characterized its physical properties on glass coverslips and glass capillary tubes. We showed that the total preparation time to coat a coverslip with HMDS is <30 minutes, which is 1 order of magnitude faster than the >12-hour protocol for coating glass surfaces with nitrocellulose. In contrast to nitrocellulose film, HMDS vapor deposition is effortless and provides an atomically flat surface with low autofluorescence. In addition, HMDS does not interfere with myosin function, which is indicated by the similar actin gliding speed when compared with nitrocellulose. Our results show that HMDS vapor deposition is a more favorable surface treatment to nitrocellulose for in vitro gliding assay.

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Norbornadiene-functionalized triazatriangulenium and trioxatriangulenium platforms

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.15.175 ◽

2019 ◽

Vol 15 ◽

pp. 1815-1821 ◽

Cited By ~ 1

Author(s):

Roland Löw ◽

Talina Rusch ◽

Tobias Moje ◽

Fynn Röhricht ◽

Olaf M Magnussen ◽

...

Keyword(s):

Functional Groups ◽

Metal Surfaces ◽

Flat Surfaces ◽

Change Mechanism ◽

Central Carbon ◽

Atomically Flat

Triazatriangulenium (TATA) and trioxatriangulenium (TOTA) ions are particularly suited systems to mount functional molecules onto atomically flat surfaces such as Au(111). The TATA and TOTA units serve as platforms that absorb onto the surface and form ordered monolayers, while the functional groups are protruding upright and freestanding from the central carbon atoms. Azobenzene derivatized TATA’s are known to exhibit extremely fast cis→trans isomerization on metal surfaces, via a peculiar non-adiabatic singlet→triplet→singlet mechanism. We now prepared norbornadienes (NBD) and quadricyclanes (QC) attached to TATA and TOTA platforms which can be used to check if these accelerated rates and the spin change mechanism also apply to [2 + 2] cycloreversions (QC→NBD).

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