X-ray fluorescence spectroscopy

Definition

X-ray fluorescence spectroscopy is an analytical technique used to determine the elemental composition of materials by measuring the fluorescent X-rays emitted from a sample when it is excited by X-ray radiation. This method leverages the unique atomic spectra produced when elements interact with X-rays, allowing for the identification and quantification of elements present in the sample based on their characteristic emission lines.

5 Must Know Facts For Your Next Test

1. X-ray fluorescence spectroscopy can analyze solids, liquids, and powders, making it a versatile tool across various fields like archaeology, environmental science, and materials analysis.
2. The intensity of the emitted fluorescent X-rays is proportional to the concentration of the elements in the sample, which allows for quantitative analysis.
3. This technique is non-destructive, meaning it does not alter or damage the sample being analyzed, making it ideal for precious or sensitive materials.
4. X-ray fluorescence can detect elements from sodium (Na) to uranium (U) depending on the energy of the X-ray source and the type of detector used.
5. Calibration with known standards is often necessary to ensure accuracy in quantifying the concentrations of elements in unknown samples.

Review Questions

• How does x-ray fluorescence spectroscopy utilize atomic spectra to identify different elements in a sample?
  • X-ray fluorescence spectroscopy identifies different elements by measuring the characteristic X-rays emitted when a sample is irradiated with X-ray radiation. Each element emits fluorescent X-rays at specific energies corresponding to its atomic structure. By analyzing these energies, which form an atomic spectrum, one can determine which elements are present in the sample and their relative concentrations.
• Discuss how the principles of selection rules apply to x-ray fluorescence spectroscopy in determining which transitions are allowed.
  • Selection rules dictate which electronic transitions are permitted based on conservation laws such as angular momentum and parity. In x-ray fluorescence spectroscopy, these rules influence which electrons can be excited to higher energy states when subjected to X-ray radiation. For instance, transitions involving core electrons are typically more probable due to favorable selection rules, affecting the intensity and detection of emitted X-rays during analysis.
• Evaluate the advantages and limitations of using x-ray fluorescence spectroscopy compared to other analytical techniques for elemental analysis.
  • X-ray fluorescence spectroscopy offers several advantages, including its non-destructive nature, ability to analyze a wide range of materials, and rapid data acquisition. However, limitations include its sensitivity to light elements, which may require specialized equipment or techniques like total reflection XRF for better detection. Additionally, matrix effects can influence results, necessitating careful calibration and standardization against known samples to ensure accurate quantitative analysis compared to methods like mass spectrometry or atomic absorption spectroscopy.

Related terms

Fluorescence: The emission of light by a substance that has absorbed light or other electromagnetic radiation, typically occurring shortly after the absorption.

Characteristic X-rays: X-rays that are emitted by an atom when its electrons transition between energy levels, unique to each element and allowing for elemental identification.

Energy Dispersive X-ray Spectroscopy (EDX): A technique used in conjunction with scanning electron microscopy that detects X-rays emitted from a sample to determine its elemental composition.