STM of freeze-fracture replicas: Problems and promises

1993 ◽  
Vol 51 ◽  
pp. 68-69
Author(s):  
J. T. Woodward ◽  
J. A. N. Zasadzinski
Keyword(s):  
Scanning Tunneling Microscope ◽  
Organic Materials ◽  
Freeze Fracture ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Molecular Scale ◽  
Organic Surfaces ◽  
Metal Layers ◽  
Conductive Surfaces

The Scanning Tunneling Microscope (STM) offers exciting new ways of imaging surfaces of biological or organic materials with resolution to the sub-molecular scale. Rigid, conductive surfaces can readily be imaged with the STM with atomic resolution. Unfortunately, organic surfaces are neither sufficiently conductive or rigid enough to be examined directly with the STM. At present, nonconductive surfaces can be examined in two ways: 1) Using the AFM, which measures the deflection of a weak spring as it is dragged across the surface, or 2) coating or replicating non-conductive surfaces with metal layers so as to make them conductive, then imaging with the STM. However, we have found that the conventional freeze-fracture technique, while extremely useful for imaging bulk organic materials with STM, must be modified considerably for optimal use in the STM.

Scanning tunneling microscopy of E. coli RNA polymerase deposited onto an Au substrate by an electrochemical process

1991 ◽  
Vol 49 ◽  
pp. 378-379
Author(s):  
Rebecca W. Keller ◽  
Carlos Bustamante ◽  
David Bear
Keyword(s):  
Scanning Tunneling Microscope ◽  
Biological Sample ◽  
Substrate Surface ◽  
Electrochemical Process ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Tunneling Microscope ◽  
E Coli ◽  
Preparation Techniques

Under ideal conditions, the Scanning Tunneling Microscope (STM) can create atomic resolution images of different kinds of samples. The STM can also be operated in a variety of non-vacuum environments. Because of its potentially high resolution and flexibility of operation, it is now being applied to image biological systems. Several groups have communicated the imaging of double and single stranded DNA.However, reproducibility is still the main problem with most STM results on biological samples. One source of irreproducibility is unreliable sample preparation techniques. Traditional deposition methods used in electron microscopy, such as glow discharge and spreading techniques, do not appear to work with STM. It seems that these techniques do not fix the biological sample strongly enough to the substrate surface. There is now evidence that there are strong forces between the STM tip and the sample and, unless the sample is strongly bound to the surface, it can be swept aside by the tip.

scholarly journals A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Xu Chen ◽  
Tengfei Guo ◽  
Yubin Hou ◽  
Jing Zhang ◽  
Wenjie Meng ◽  
...  
Keyword(s):  
Scanning Tunneling Microscope ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Electronic Noise ◽  
High Quality ◽  
Tunneling Microscope ◽  
The Core ◽  
High Rigidity ◽  
The Common ◽  
The Impact

A new scan-head structure for the scanning tunneling microscope (STM) is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans) coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan). They are fixed at one end (called common end). A hollow tantalum shaft is coaxially housed in the XY-scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

Ultrahigh vacuum STM studies of the Bi–O surface of Bi2212

1992 ◽  
Vol 7 (5) ◽  
pp. 1060-1062 ◽  
Author(s):  
Kazuto Ikeda ◽  
Kenshi Takamuku ◽  
Koji Yamaguchi ◽  
Rittaporn Itti ◽  
Naoki Koshizuka
Keyword(s):  
Single Crystals ◽  
Scanning Tunneling Microscope ◽  
Ultrahigh Vacuum ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscope

Observations of the Bi–O surface of superconductive Bi2212 single crystals were carried out using an ultrahigh-vacuum scanning tunneling microscope (UHV-STM). In the atomic resolution images, surface corrugations, which correspond to the superstructure of the Bi–O surface in addition to Bi atom deficiencies, were observed. There were hollow lines along the ridges of the corrugations, which may be due to missing atom rows.

Atomic resolution images of metal surfaces exposed in oil using a scanning tunneling microscope

1990 ◽  
Vol 68 (5) ◽  
pp. 2528-2529 ◽  
Author(s):  
T. Endo ◽  
H. Yamada ◽  
T. Sumomogi ◽  
K. Kohno ◽  
K. Kuwahara ◽  
...  
Keyword(s):  
Scanning Tunneling Microscope ◽  
Metal Surfaces ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscope

A two-spring model of the tip-sample interaction using the Scanning Tunneling Microscope in air

1991 ◽  
Vol 49 ◽  
pp. 382-383
Author(s):  
John T. Woodward
Keyword(s):  
Liquid Bridge ◽  
Scanning Tunneling Microscope ◽  
Freeze Fracture ◽  
Tunneling Current ◽  
Sample Surface ◽  
Scanning Tunneling ◽  
Weakly Bound ◽  
Electrically Conductive ◽  
Tunneling Microscope ◽  
Piezoelectric Drive

The scanning tunneling microscope (STM) is capable of imaging surface features of electrically conductive samples with lateral resolution of 2 Angstroms and vertical resolution of 0.1 Angstroms. This is accomplished by rastering a conducting tip just above the sample surface using a piezoelectric drive. The tunneling current between the tip and the sample, which depends on the distance separating the two, is then used to keep the tip a constant distance above the sample and generate a height plot of the surface.When an STM is used in air, a small liquid bridge can be formed between the scanning tip and the sample as shown in Fig. 1, This bridge results from any fluid contamination on the surfaces along with condensation of primarily water from the air. For most applications of the STM, this liquid bridge has little effect on the image. However if the sample is somewhat flexible or only weakly bound on the STM base, as is the case for freeze fracture replicas, the forces exerted by the liquid bridge on the sample as the tip scans the surface can significantly alter measured heights from their actual values.

Design and application of a scanning tunneling microscope for the observation of large machined surfaces

1989 ◽  
Vol 47 ◽  
pp. 26-27
Author(s):  
D.A. Grigg ◽  
T. A. Dow ◽  
P. E. Russell
Keyword(s):  
Scanning Tunneling Microscope ◽  
Metal Surfaces ◽  
Single Point ◽  
Semiconductor Materials ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Large Sample ◽  
Microscopic Studies ◽  
Design And Application ◽  
Conductive Surfaces

The scanning tunneling microscope is an instrument which can be used to image conductive surfaces with angstrom resolution. This makes the STM an ideal instrument for microscopic studies on machined metals and semiconductors. Several papers have been published showing the effectiveness of the scanning tunneling microscope (STM) to image single point diamond turned metal surfaces such as gold and aluminum.A large sample STM has been constructed specifically to handle machined samples as large as 76 mm in diameter (Fig. 1). A tube scanner has been implimented which allows scan lengths of up to 10 μm. The STM has been designed for quick and easy sample/tip exchange.STM studies have been made on single point diamond turned metals and semiconductor materials. Two forms of copper were diamond turned and studied using the large sample STM;

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