Module 6 Glossary

De-excite

To de-excite an electron, it must lose energy to transition to a lower energy state.

Electron Orbitals

The shapes or directions electrons move as they revolve around the nucleus of an atom.

Excite

To excite an electron is to give the electron enough energy to be raised to a higher energy state. Any electron above the lowest energy state (ground state) is an excited electron.

Fluorescence

The emission of light or a photon by an element's electrons as they de-excite.

Photon

In the context of the TREE program and with XRF interpretation, a photon is the fluoresced X-ray.

Planetary Model

A model used to visually represent the structure of an atom. Developed by scientist Niels Bohr, this model shows electron orbitals as distinct circles surrounding the nucleus of the atom. This model is used in the TREE program to explain XRF.

Primary Peak

In an XRF graph, when looking at a specific element, this is the largest peak from the most likely electron transition of that element. This peak shows that less energy is used to make this transition occur than the secondary peak

Quantum Model

Another model used to visually represent the structure of an atom. Developed by scientist Erwin Schrodinger, this model shows the electron orbitals as waves surrounding the nucleus of the atom.

Relative Elemental Concentration

In XRF graphs, the peak height within one sample can be compared to each other such that a higher peak of one element indicates more of that element. However, with relative elemental concentration, scientists are NOT able to compare between different samples without more intensive techniques.

Ring Width Index (RWI)

The RWI tells the dendrochronologist which rings were above or below the tree's average growth which indicates if the tree's environmental conditions were suitable or not.

Secondary Peak

In an XRF graph, when looking at a specific element, the secondary peak is the next largest peak from the second most likely electron transition which will require a bit more energy to make this transition occur. This peak is not always seen in the graph as it may be overlapped with another elemental peak and that is important to be aware of when interpreting data.

Waterfalled

When graphing, this term refers to when data is layered on a graph which allows researchers to look at differences in XRF scans as the years progress.

X-ray Fluorescence

An analysis technique the IDEAS beamline uses that is able to tell what elements are present and absent in a sample.

X-ray Fluorescence Line Scan

Similar to XRF, this is another analysis technique the IDEAS beamline uses that is able to tell what elements are present and absent as a specific spot is analyzed, the sample moves in a linear fashion, and another spot is analyzed and on and on until the scan stops.

XRF Graph

A plot of the intensity or the number of X-rays (or other energy photons) counted vs their energy. The height of the peaks is related to the number of the X-rays that hit our detector (or the photon count) at that specific energy.

XRF Line Scan Graph

A graph of line scan data that is plotted as the normalized photon count of a single element vs the position along the sample or in the case of the TREE program, the tree core.