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SCANNING ELECTRON MICROSCOPE

Introduction

The Scanning Electron Microscope (SEM) allows visualization of surface features of a solid sample by scanning through an

electron beam. SEM has better resolution capability and depth of field than a light microscope. As a result of which very good

quality three dimensional like images are obtained. In advanced SEM machine, magnification can range from 10× to 5, 00, 000×

and resolution of about 1 nm. This is about 250 times the magnification limit of the best light microscope.

SEM facility at Bombay Textile Research Association is housed in the main building. People from textile industry, pharmaceutical

industry, ceramic industry, polymer industry and other allied industries, and university students regularly come here for testing

their samples.

Figure: SCANNING ELECTRON MICROSCOPE JEOL JSM 5400 at BTRA

The SEM Facility is equipped with following equipments:

SCANNING ELECTRON MICROSCOPE- JEOL JSM 5400

PROJECTION MICROSCOPE-ERNST LEITZ WETZLAR

POLARIZING MICROSCOPE-CARL ZEISS

GOLD / SILVER SPUTTER COATING UNIT

What is Scanning Electron Microscopy?

The major component of a SEM is shown in the following figure. A beam of electrons is produced from a tungsten

filament by thermionic emission which is accelerated in a high vacuum towards an anode. The emerging electron beam

is focused and scanned over the sample surface using a pair of magnetic lenses. This beam of electron is called

primary electrons. Electrons of primary beam interact with the matter of sample. Interaction provides a variety of signals

such as secondary electrons (SE), elastically scattered backscattered electrons (BSE) and X-rays. These are used for

various purposes such as given in the table.

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Figure: Components of a SEM

Table: Signals in SEM and their utility

Signal Utility

Secondary electrons (SE) Surface morphology (features)

Backscattered electrons (BSE) Composition contrast and surface topography

X-rays Elemental analysis

Samples which can be analyzed

A wide range of materials whose morphology can be routinely analyzed include :

Metals, Glass, Ceramics and Polymers

Semiconductors

Plastics

Fibers (Textile, Glass, Asbestos, Natural)

Powders and Dust

Pharmaceutical powder, pellets, capsules

Samples can be analyzed provided these are vacuum compatible and not damaged by heat produced by electron

beams.

Sample Preparation Procedures

For our SEM, the conventional sample holder size is 2.5 cm × 2 cm (rectangular) and a diameter of 1 cm (round). So, the size of mounted sample is limited by that dimension. Before a sample can be observed with the SEM, it is often necessary to carry out gold or silver coating to make the sample conductive. For conductive samples like metals, coating step is not required.

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Figure: Gold sputter coater (left) and sample holders (right)

Range of applications

Examination of surface morphology

Defect analysis of textile materials

Cross-section and longitudinal imaging of filaments/yarns

Powder morphology, particle size and analysis

Frequently asked questions

1) What is surface morphology?

It is about the shape, size, textures and features present on the sample surface.

2) Will coating destroy the sample surface morphology?

No, the gold/silver coating is too thin to hide the sample morphology.

3) Can our suspension be analyzed?

Samples which contain volatile liquids can be analyzed.

4) Can SEM give the quantitative information?

SEM provides micrographs with scales which can be used to get some quantitative information like

the distance between two points on the micrograph. It can also be used to find the pore size, shape of

a feature. But, it does not provide topographical height information like AFM does.

5) Can we analyze porous material?

We can see the pore size and its shape but for the quantitative determination of degree of porosity

other kind of tests is required.

6) Can we find the color images?

SEM originally gives black and white images. Nowadays, some feature extracting softwares are used

to generate color of the sample surface features.

7) How to contact for SEM analysis?

Kindly call our laboratory manger at the following ‘contact us’ for further details.

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Contact us

BTRA Test Laboratories: For testing related enquires such as type of tests conducted, test charges, delivery time, etc.

E-mail: btralabs@gmail.com

Telephone: 091-022-25001811

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A Gallery of SEM Lab Images

Cross-sectional Images Longitudinal Defects Porous

Biological Samples Pharmaceutical drugs Spinneret Cosmetics

Paints Ceramics

CROSS-SECTIONAL IMAGES OF FIBRES

HOLLOW POLYESTER

NYLON

LONGITUDINAL IMAGES

WOOL

COTTON

FABRIC DEFECT: HOLES IN THE FABRIC

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PHARMACEUTICAL AND BIOLOGICAL SAMPLES

MACIM (DRUG)

ACTINOMYCETE CULTURE

CURCUMIN DRUG

POLYMER SCAFFOLD

OTHER SEM IMAGES

PHOSPHATED PAINT PANEL REPLICA OF SPINNERETTE

WELD METAL

TALC POWDER

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Our Top Customers

Pulp and Fibre Innovation Centre

Bharat Serums & Vaccines limited

Reliance Industries Ltd.

Cipla Ltd.

ACG Associated Capsules

Ferring Pharmaceuticals

Dcm Shriram Industries Ltd.

Cadila Pharmaceuticals

Lupin Pharmaceuticals

The Dow Chemical Company

Diversey India Pvt. Ltd.

Ganesh Ecospheres Ltd.

IPCA

Getz Pharma Research

Institute Of Chemical Technology

Wool Research Association

Some Useful Links

1. http://en.wikipedia.org/wiki/Scanning_electron_microscope

2. http://www.jeolusa.com/tabid/320/Default.aspx?EntryId=598

3. http://science.howstuffworks.com/scanning-electron-microscope2.htm