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Identification of Isotopes Present in a Material by Dynamic Secondary Ion Mass Spectrometry (D-SIMS) (CAT#: STEM-ST-1813-CJ)

Introduction

Isotopes are distinct nuclear species (or nuclides, as technical term) of the same element. They have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), but differ in nucleon numbers (mass numbers) due to different numbers of neutrons in their nuclei.




Principle

Dynamic SIMS uses a continuous, focused beam of primary ions to remove material from the surface of a sample by sputtering. The fraction of sputtered material that is ionized is extracted into a double-focusing mass spectrometer, which uses electrostatic and magnetic fields to separate the ions according to their mass-to-charge ratio. Ions of different mass-to-charge ratios are selected by adjusting the strength of the magnetic field. Dynamic SIMS is extremely sensitive—able to detect fractions in the range of parts per million to parts per billion—and is used to determine the elemental composition and levels of trace impurities and dopants in solid materials.

Applications

Element Analysis

Procedure

1. Sample preparation: The sample is prepared by cleaning it to remove any contaminants that could interfere with the analysis. The sample may also be coated with a thin layer of conductive material to prevent charging during analysis.
2. Primary ion bombardment: The sample is bombarded with a beam of high-energy primary ions, typically from an ion gun. The primary ions interact with the atoms on the surface of the sample, causing the ejection of secondary ions, neutrals, and electrons.
3. Secondary ion extraction: The secondary ions are extracted from the sample surface using a high voltage electric field. The extracted ions are accelerated towards the mass spectrometer.
4.Mass separation: The ions are separated by their mass-to-charge ratio (m/z) using a mass spectrometer. The ions are then detected by an ion detector, which measures their abundance.
5. Data analysis: The data is analyzed to determine the elemental and isotopic composition, as well as the chemical structure and molecular fragmentation patterns of the sample. This information can be used to identify the material and understand its properties and behavior.

Materials

• Sample: Solid thin layer; Flat surface material; Powder; Metals; Semiconductors and Insulators & More
• Equipment: Dynamic Secondary Ion Mass Spectrometry (D-SIMS) instruments

Notes

1. Highest chemical sensitivity for trace elements and molecular fragments among all surface analysis techniques.
2. Able to detect all elements H to U (This is the only surface analysis technique for directly detecting hydrogen and deuterium in materials).
3. Powerful chemical mapping capability: each pixel in a map and each point in a depth profile contain a full spectrum of all mass peaks which can be selectively extracted.
4. Compared with TOF-SIMS, D-SIMS has a stronger depth analysis ability, the analysis depth can reach 5-10um, and the element information can be continuously tested during the analysis process.
5. D-SIMS can produce acutely sensitive depth profiles of compositional distribution with nm-scale vertical resolution.
6. Not quantitative without calibration to standards / reference of known compositional matrix.