Energy-Dispersive X-ray Spectroscopy: Measurement Demonstration

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来自 Duke University 的课程

Nanotechnology: A Maker’s Course

424 个评分

Duke University

Nanotechnology: A Maker’s Course

424 个评分

How can we create nano-structures that are 10,000 times smaller than the diameter of a human hair? How can we “see” at the nano-scale? Through instruction and lab demonstrations, in this course you will obtain a rich understanding of the capabilities of nanotechnology tools, and how to use this equipment for nano-scale fabrication and characterization. The nanoscale is the next frontier of the Maker culture, where designs become reality. To become a Nanotechnology Maker pioneer, we will introduce you to the practical knowledge, skills, and tools that can turn your nanotechnology ideas into physical form and that enable you to image objects at the nano-scale. This course has been developed by faculty and staff experts in nano-fabrication, electron beam microscopy, and nano-characterization through the Research Triangle Nanotechnology Network (RTNN). The RTNN offers training and use of the tools demonstrated in this course to schools and industry through the United States National Nanotechnology Coordinated Infrastructure program. The tools demonstrated in this course are available to the public through the RTNN.

从本节课中

Nano Measurement and Characterization Tools: Scanning Electron Microscopy and Energy-Dispersive X-ray Spectroscopy

After this module, you will be able to explain sample preparation and imaging techniques used in scanning electron microscopy. You will also be able to explain the benefits of environmental scanning electron microscopy. Furthermore, you will discover how energy-dispersive x-ray spectroscopy can be paired with scanning electron microscopy to gain elemental information about samples.

Energy-Dispersive X-ray Spectroscopy: Basic Function4:43

Energy-dispersive X-ray Spectroscopy: Sample Preparation Demonstration2:17

Energy-Dispersive X-ray Spectroscopy: Measurement Demonstration4:16

与讲师见面

Nan M. Jokerst
J. A. Jones Professor of Electrical and Computer Engineering
Electrical and Computer Engineering, Duke University
Carrie Donley
Director of CHANL (Chapel Hill Analytical and Nanofabrication Laboratory)
Applied Physical Sciences, UNC Chapel Hill
James Cahoon
Assistant Professor
Chemistry, UNC Chapel Hill
Jacob Jones
Professor
Materials Science and Engineering, North Carolina State University

Hello.

I'm Roberto Garcia.

I'm a lab manager at the Analytical Instrumentation Facility at NC State University,

part of the Research Triangle Nanotechnology Network.

In this video, you will learn how to perform

an energy dispersive X-ray spectroscopy experiment or EDS experiment on a sample.

Make sure your sample is prepared appropriately

on a compatible mount for your electron microscope.

Today, we're going to identify elements present in a piece of stainless steel.

Our sample is mounted on a Hitachi screw mount using double-sided carbon tape.

Using gloves to handle your sample,

place the mount on the stage.

It needs to be secured enough to make sure that the mount won't slip

off the stage if we want to tilt the sample inside the chamber.

Today, we will be performing our EDS experiment on

a Hitachi S3200 variable-pressure scanning electron microscope, or SEM.

First, we vent the chamber so we can open it and put our sample inside.

After the chamber has vented,

the sample can be loaded.

Place the sample securely onto the stage.

Carefully slide the sample back into the chamber and pump it back under vacuum.

Once the chamber reaches appropriate pressure,

turn on the high voltage,

or HV, to turn on the electron beam.

Adjust brightness and contrast until the sample is visible.

Find the region of interest and bring it into focus

at your desired magnification and working distance.

Working distance is the distance between the sample and

the pole piece or the beam exits the electron column.

The optimal working distance for

EDS experiments will be different for each different microscope.

It is critical to focus and align the beam at

this working distance for a good EDS experiment.

For our setup, working distance should be around 18 millimeters.

Now that we have our region of interest and focus at optimal working distance,

we are ready to perform our EDS experiment.

To start our experiment,

we must insert the X-ray detector or EDS detector.

Detectors may be inserted manually or automatically through the EDS software.

Once the detector is inserted,

we open up the EDS analysis software.

The one we use on this microscope is called Revolution.

Now, we begin our scan to collect signal from a region of interest.

We can scan the entire region in view and get

an idea of all elements present in our image.

A spectrum begins to form.

This is a live feed of the software counting X-rays at different energies.

We can match these spectral fingerprints to a database to identify the elements

present and cycle through all elements on the periodic table.

Once the bars line up with our peaks,

we can be confident that the element is present.

From these peaks, it looks like we have some nickel,

iron, and chromium in our sample.

We can also collect signal from a very specific region or feature using

localized signal collections like line scans or smaller area scans.

Let's try a small area scan on this region here.

Draw a box around the region of interest.

Now, the software will collect signal from this area alone.

These types of localized scans are useful for

determining the composition of a particular feature.

Some samples may have a varying elemental compositions in different areas.

Since we have identified the elements present in our region of interest,

our experiment is complete.

We can turn the beam off and remove our sample now.

Retract the EDS detector, vent the chamber,

remove the sample from the chamber,

finally, close the chamber and pump back under vacuum.

We are now done with our EDS experiment.

Because EDS is a non-destructive technique,

we can save our sample and come back any time to

replicate our experiment or try other conditions.

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