A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons.
Scanning Probe microscopy (AFM and STM) head point
AFM: Configuration of AFM
Parts of AFM system and Principle of AFM
Three Modes of AFM
AFM Instrument
Advantage and disadvantage
STM
Schematic Diagram
AFM and STM
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A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons.
Scanning Probe microscopy (AFM and STM) head point
AFM: Configuration of AFM
Parts of AFM system and Principle of AFM
Three Modes of AFM
AFM Instrument
Advantage and disadvantage
STM
Schematic Diagram
AFM and STM
https://www.linkedin.com/in/preeti-choudhary-266414182/
https://www.instagram.com/chaudharypreeti1997/
https://www.facebook.com/profile.php?id=100013419194533
https://twitter.com/preetic27018281
Please like, share, comment and follow.
stay connected
If any query then contact:
chaudharypreeti1997@gmail.com
Thanking-You
Preeti Choudhary
Transmission electron microscopy (TEM)- by sivasangari Shanmugam. Transmission electron microscopy (TEM) is a technique used to observe the features of very small specimens.
Surface Plasmon Resonance,
Surface Plasmons:
Plasmons confined to surface (interface) and interact with light resulting in polarities.
Propagating electron density waves occurring at the interface between metal and dielectric.
• The scanning tunneling Microscope is an electron microscope that transmits three - dimensional images of the electron cloud around the nucleus.
• The scanning tunneling Microscope (STM) works by scanning a very sharp metal wire tip over a surface. By bringing the tip very close to the surface, and by applying an electrical voltage to the tip or sample, we can image the surface at an extremely small scale - down to resolving individual atoms.
Transmission electron microscopy (TEM)- by sivasangari Shanmugam. Transmission electron microscopy (TEM) is a technique used to observe the features of very small specimens.
Surface Plasmon Resonance,
Surface Plasmons:
Plasmons confined to surface (interface) and interact with light resulting in polarities.
Propagating electron density waves occurring at the interface between metal and dielectric.
• The scanning tunneling Microscope is an electron microscope that transmits three - dimensional images of the electron cloud around the nucleus.
• The scanning tunneling Microscope (STM) works by scanning a very sharp metal wire tip over a surface. By bringing the tip very close to the surface, and by applying an electrical voltage to the tip or sample, we can image the surface at an extremely small scale - down to resolving individual atoms.
electron scattering,SEM,TEM,tunnel effect and lensesKASHISHMANGAL2
it can give you the brief view about the effects and lense used for electron microscope i.e. SEM,TEM,electron scattering,tunnel effect,electrostatic lens and magnostatic lens
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is guided through an ultra thin specimen, interacting with the specimen as it passes through.An image is formed from the fundamental interaction of the electrons transmitted through the specimen; the image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film, or to be observed by a sensor such as a CCD camera.
In our conventional electronic devices we use semi conducting materials for logical operation and magnetic materials for storage, but spintronics uses magnetic materials for both purposes. These spintronic devices are more versatile and faster than the present one. One such device is Spin Valve Transistors (SVT).
Spin valve transistor is different from conventional transistor. In this for conduction we use spin polarization of electrons. Only electrons with correct spin polarization can travel successfully through the device. These transistors are used in data storage, signal processing, automation and robotics with less power consumption and results in less heat. This also finds its application in Quantum computing, in which we use Qubits instead of bits.
A Scanning Electron Microscope (SEM) is a powerful magnification tool that utilizes focused beams of electrons to obtain information. The high-resolution, three-dimensional images produced by SEMs provide topographical, morphological and compositional information makes them vital in science and industry.
An introduction to nano-science and nanotechnology, now in English !!
I am sorry about mistakes like "Fisics" instead of "Physics" and "alone atoms" where should be "sinlge atoms".
=)
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
2. 1. INTRODUCTION
The scanning tunneling microscope (STM) is a magnificent microscope ever built. It was generated in
1981 by Gerd Binning and Heinrich Rohrer of IBM’s Zurih Lab in Zurich,Switzerland. The invention
deserved Nobel prize for physics in 1986.
On October, 1986, the soccer team of IBM Zurich Laboratory
and Down Chemical played a game which had been arranged
earlier. To everyone’s surprise, a few hours before the game,
The Sweedish Academy announced the Nobel Prize for Gerd
Binning ( right ) and Heinrich Rohrer ( left ).
3. The Scanning Tunneling Microscope is an electron
microscope that transmit three-dimensional images of the
electron cloud around the nucleus.
The STM allows the inspection of the properties of a
conductive solid surface at an atomic size.
It is a very important technique in determining the atomic
structures and electronic states of the surface under
investigation.
Surfaces can be viewed at the atomic size thanks to the
high resolution (0.1 Ǻ) that STM has.
4. Basic components of STM
Five basic components:
1. Metal tip,
2. Piezoelectric scanner,
3. Current amplifier (nA),
4. Bipotentiostat (bias),
5. Feedback loop (current).
The scanner
can be
mounted with
the tip or the
sample stage.
5.
6. 2.TUNNELING EFFECT
The basis of STM is the quantum tunneling theory.
According to quantum tunneling theory, when the energy
of an electron exceeds its total energy, it can penetrate
regions which are impossible according to classical
physics. So it can tunnel.
In other words, if two conductors are brought closer to
each other by 10 Ǻ or more and a potential difference is
created between them, the electrons are likely to tunnel
through the potential barrier between these two
conductors.
7. 2.1.GENERATING TUNNELING CURRENT
A tunneling current occurs when electrons move through a barrier that they shouldn't be able to move
through in classic physics. In classical terms, if you don't have enough energy to move "over" a
barrier, you won't. However, in quantum mechanical world, electrons have wavelike properties. These
waves don’t end suddenly at a wall or barrier, but taper off quickly. If the barrier is thin enough, the
probability function can expand into the next region, through the barrier.
If a very sharp metal tip, called a probe (atomic size), is approached to the surface to be investigated
by a mechanical system (1-10 Ǻ) and a potential difference is applied, the wave functions of the type
and the surface superimpose and electrons are superimposed on the surface, A current is generated
called tunneling current.
A probe tip, usually made of W or Pt–Ir alloy. The tip is mechanically connected to the scanner, an
XYZ position device realized by means of piezoelectric materials. Distance between tip and surface
must be 1Å to 10Å.
8. 2.2. DIRECTION OF TUNNELING CURRENT
The direction of flow depends on the sign of the applied
potential.
If the sample is negatively charged, the electrons will pass
through the filled orbital of the sample to the empty orbital
of the tip.
The flow here is very small and at nA level.
9. 3.WORK PRINCIBLE OF STM
When voltage is generated between a specimen and a
tip with a very small distance (a few angstroms), due
to the quantum tunneling, there is an electron
transition from the specimen to tip or from tip to
specimen, which corresponds to a tunnel current at
the picoamper stage.
This tunneling current, which occurs when scanning
the specimen on the specimen surface, is measured
and is used to obtain surface tomography, since this
current is a function of the distance between the
specimen and the tip.
10. In constant-height mode, the tip scan in a horizontal plane above the
sample and the tunneling current varies depending on topography and
the local surface electronic properties of the sample. The tunneling
current measured at each location on the sample surface constitute the
data set, creating the topography image in figüre (a)
In the constant-current mode, by adjusting the height of the type, the
current is held constant by the feedback circuit which keeps the
current constant and is moved on the type surface. During this time,
changes are recorded in the height of the height of the image is
created. Showed as figüre (b)
11. 3.2. DISTANCE BETWEEN TIPAND SPECIMEN
The tunneling current varies exponentially depending on the distance
between the individual specimens.
It = Ve-kd
V: potential difference between conductors.
k: constant which depends on conductors composition
d: distance between the lowest (nearest to the sample) atom on the tip
and the highest (nearest) atom on the sample.
If the distance increases, the tunneling current (It) will decrease
exponentially.
12. 4. TIP PROPERTIES
The most important part of the scanning tunneling microscope is the tips.
The tunneling tip, provides the best images that are limited by a single metal
atom of the tip.
The traces were obtained by cutting the platinum / iridium wires or by
electrochemically etching the tungsten metal. At the present time,
electrochemical etching of Pt / Ir wires yields very clear solubility types
Close-up view of a Pt-Ir type
with a diameter of 0.25 mm
used in STM work.
13.
14. FACTORS EFECTING THE RESOLUTION
• One of the factors affecting resolution is corrugation, i.e. how much the electron density of surface
atoms varies in height above the surface.
• Graphite has a large corrugation, and is very planar, and thus is one of the easiest materials to image
with atomic resolution. (see next slide for example)
• STM does NOT probe the nuclear position directly, but rather it is a probe of the electron density, so
STM images do not always show the position of the atoms. STM imaging depends on the nature of the
surface and the magnitude and sign of the tunneling current. For example, if you have Cu and Si on the
same surface, under the same condition, the current with Cu is much higher .
15.
16. POSITIONING
The large distance range the tip has to be controlled on makes it necessary to use two positioners: a
coarse and a fine positioner.
The fine positioner is also used as a scanner. Every fine positioner/scanner is made out of a piezocrystal
or piezoceramic material.
17. 5. PIEZOELECTRIC EFECT
The piezoelectric effect was discovered by Pierre Curie in 1880. The effect is created by squeezing the
sides of certain crystals, such as quartz .The result creates of opposite charges on both sides. The effect can
be reversed as well; by applying a voltage across a piezoelectric crystal, it is going to be elongate or
compress.
The process is based on fundamental structure of a Crystal lattice crystals generally have a charge balance
where negative and positive charges precisely nullify eac other out along the rigid planes of the crystal
lattice. When this charge balance is disrupted by an external force, such as, applying physical stress to a
Crystal, the energy is transferred by electric charge carries, creating a surface charge density, which can be
collected via electrodes.
20. STM ADVANTAGES
STMs are helpful because they can give researchers a three dimensional profile of surface, which
allows researchers to analysis a multitude of characteristics, including roughness, surface defects and
determining things about the molecules size and conformation.
It is capable of capturing much more detail than other microscopes. This helps researchers better
understand the subject of their research on molecular level.
STMs are also versatile. They can be used for ultra high vacuum, air, water and other liquids and gasses.
They will activate in temperatures as low as zero Kelvin up to a few hundred degrees Celsius.
Scanning Tunneling Microscope works faster than Atomic Force Microscope.
AFM max sample size is 150x150 µm. On the other hand, STM generates mm size length and width.
Lastly, resolution of STM is much better than AFM.
21. STM DISADVANTAGES
There are very few disadvantages to using a scanning tunneling microscope.
STMs can be difficult to use effectively. There is very specific technique that requires a lot of
skill and precision.
STM requires very stable and smooth surfaces, excellent vibration control and sharp tips.
STMs use highly specialized equipment that is fragile and expensive.
Although, STM analysis only conductive materials, AFM uses for conductive and insulator
materials.
STM requires vacuum atmosphere but AFM can work even in liquid. For that reason AFM
can be used for biological materials.
22. REFERENCES
2. J. Chen, Introduction to Scanning Tunneling Microscopy, New York, Oxford
Univ. Press (1993).
Gan, Y., Chu, W., & Qiao, L. (2003). STM investigation on interaction between superstructure and grain
boundary in graphite. Surface Science, 539(1), 120-128.
Marti, O., & Amrein, M. (Eds.). (2012). STM and SFM in Biology. Academic Press..
Microscopy (pp. 59-67). Springer Netherlands.
http://jdetrick.blogspot.com.tr/2012/03/scanning-tunneling-microscope-and-3-d.html
http://www.nanoscience.com/technology/scanning-tunneling-microscopy/how-stm-works/