Adele Hochberg

Adele Hochberg

Apr 30, 2017

Group 6 Copy 14
0

Information on EDS

EDS is a technique used in conjunction with field emission scanning electronmicroscopy (FE-SEM). When the electron beam from the FE-SEM hits the sample, it ejects an e- from an inner shell (e.g., K shell, see below) that is replaced with an e- from a higher-energy outer shell. The difference in energy levels between these electrons is given off as a characteristic x-ray. The x-rays are then displayed graphically as an EDS spectrum (see figure, below). Each element and its corresponding shells have their own diagnostic x-ray spectral peaks that are easily visualized. Taking the integral of the peaks in the spectrum gives the relative abundance of each element present in the scanned area, providing both the atomic and weight percentages for each element. However, the voltage of the electron beam limits how far the beam can penetrate into the specimen. For example, a 20kV beam penetrates 4.10 μm of pure carbon but only 0.5 μm of pure gold. A normally coated specimen for FE-SEM is covered by only several Å of gold, meaning that an electron beam will penetrate both the gold coating and approximately 4 μm of specimen.


0 comments

Join the conversation!Sign In

About This Project

University of Massachusetts Lowell

Energy dispersive x-ray spectroscopy (EDS) is a method for analyzing the elemental (chemical) composition of synthetic and natural structures, and has been useful in identifying trace metals in forensics and ecotoxicology. To date, it has never been applied to detect trace elements in invertebrate secretions. Here, I describe a study that uses EDS to characterize the protective secretions of sessile rotifers and to determine if metal pollutants are incorporated into their secretions.

More Lab Notes From This Project

Blast off!

Browse Other Projects on Experiment

Related Projects

Wormfree World - Finding New Cures

Hookworms affect the lives of more than 400,000,000 men, women and children around the world. The most effective...

Viral Causes of Lung Cancer

We have special access to blood specimens collected from more than 9,000 cancer free people. These individuals...

Cannibalism in Giant Tyrannosaurs

This is the key question we hope to answer with this study. This project is to fund research into a skull...

Add a comment