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Posted Date: July 1, 2017

FIG. 3. Averaged I-V data obtained for (A) Al7 and (B) Al5 monolayers recorded under various tip loading forces. Solid and open circles represent the data obtained when the tip is magnetized with positive (H+) and negative (H−) magnetic fields (±1 T), respectively. (C) Variations of spin polarization (P) measured at 1 V as a function of the loading force of Al5 (red) and Al7 (blue) monolayers.

Abstract
The chiral-induced spin selectivity (CISS) effect entails spin-selective electron transmission through chiral molecules. In the present study, the spin filtering ability of chiral, helical oligopeptide monolayers of two different lengths is demonstrated using magnetic conductive probe atomic force microscopy. Spin-specific nanoscale electron transport studies elucidate that the spin polar- ization is higher for 14-mer oligopeptides than that of the 10-mer. We also show that the spin filtering ability can be tuned by changing the tip-loading force applied on the molecules. The spin selectivity decreases with increasing applied force, an effect attributed to the increased ratio of radius to pitch of the helix upon compression and increased tilt angles between the molecular axis and the surface normal. The method applied here provides new insights into the parameters controlling the CISS effect. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). [http://dx.doi.org/10.1063/1.4966237]

Reference:
The Journal of Chemical Physics 146.9 (2017)

Credits:
Vankayala Kiran1, Sidney R. Cohen2, and Ron Naaman1

1Department of Chemical Physics, Weizmann Institute of Science, Rehovot NA 76100, Israel
2Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel

Microscope:
RHK Big G High-Field Magnet SPM

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Panscan Freedom SPM,  VT Beetle
Events
Event Date: June 23, 2017

June 27 – 29 in Portland, Oregon, USA

77th annual Physical Electronics Conference

The Conference will be held at the University Place Hotel and Conference Center at Portland State University.

http://physelectronics.com/

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Image of the Month
Posted Date: June 1, 2017

Fig. 2. STM topography image of carbon-induced islands intercalated between MoS2 layers and Current-voltage (I(V)) spectroscopy curves recorded on top of an island and on the surrounding MoS2 layer. The same characteristic I(V) behavior is measured, which unequivocally demonstrates that the island is intercalated and is covered with the same material as the surroundings, i.e., MoS2. The I(V) curves appear to be metallic, since the set point used in order to record them is within the band gap of MoS2. The set points are 0.2 nA, 0.5 V

Abstract
Direct growth of flat micrometer-sized bilayer graphene islands in between molybdenum disulfide sheets is achieved by chemical vapor deposition of ethylene at about 800 _C. The temperature assisted decom- position of ethylene takes place mainly at molybdenum disulfide step edges. The carbon atoms interca- late at this high temperature, and during the deposition process, through defects of the molybdenum disulfide surface such as steps and wrinkles. Post growth atomic force microscopy images reveal that cir- cular flat graphene islands have grown at a high yield. They consist of two graphene layers stacked on top of each other with a total thickness of 0.74 nm. Our results demonstrate direct, simple and high yield growth of graphene/molybdenum disulfide heterostructures, which can be of high importance in future nanoelectronic and optoelectronic applications.

2017 Elsevier Inc. All rights reserved.

Reference:
Journal of Colloid and Interface Science 505 (2017): 776-782.

Credits:
Wojciech Kwieciñskia,b, Kai Sotthewesa, Bene Poelsemaa, Harold J.W. Zandvlieta, Pantelis Bampoulisa,c

aPhysics of Interfaces and Nanomaterials, MESA+Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands


bFaculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
cPhysics of Fluids and J.M. Burgers Centre for Fluid Mechanics, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands

Microscope:
UHV Beetle AFM/STM

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PRIcon
Image of the Month
Posted Date: May 1, 2017
iotm-may-2017-thumb

Figure 3. Scanning tunneling microscopy images of Aβ1−16-Cu2+ (a,b) and Aβ1−16 (c,d). Imaging conditions: (a,b) 10 nm × 10 nm, Vsample = 0.55 V, Itunnel =10pA;(c)10nm×10nm,Vsample =0.25V,Itunnel =17pA;(d)10nm×10nm,Vsample =0.30V,Itunnel =14pA.

Abstract
β-Amyloid aggregates in the brain play critical roles in Alzheimer’s disease, a chronic neurodegenerative condition. Amyloid-associated metal ions, particularly zinc and copper ions, have been implicated in disease pathogenesis. Despite the importance of such ions, the binding sites on the β-amyloid peptide remain poorly understood. In this study, we use scanning tunneling microscopy, circular dichroism, and surface-enhanced Raman spectroscopy to probe the inter-actions between Cu2+ ions and a key β-amyloid peptide fragment, consisting of the first 16 amino acids, and define the copper−peptide binding site. We observe that in the presence of Cu2+, this peptide fragment forms β-sheets, not seen without the metal ion. By imaging with scanning tunneling microscopy, we are able to identify the binding site, which involves two histidine residues, His13 and His14. We conclude that the binding of copper to these residues creates an interstrand histidine brace, which enables the formation of β-sheets.

Reference:
Nano Letters 2016, 16, 6282-6289

Credits:
Diana Yugay,†,‡ Dominic P. Goronzy,†,‡ Lisa M. Kawakami, Shelley A. Claridge,‡,§,∥ Tze-Bin Song, ZhongboYan, Ya-HongXie,*,†,⊥ Jeŕom̂eGilles,*,∇ YangYang,*,†,⊥ and PaulS.Weiss*,†,‡,⊥

California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
§Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
Department of Mathematics and Statistics, San Diego State University, San Diego, California 92182, United States

Microscope:
Agilent Pico SPM

Control System:
RHK R9

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