Glow-discharge optical emission spectroscopy (GDOES) is a spectroscopic method for the quantitative analysis of metals and other non-metallic solids. The idea was published and patented in 1968 by Werner Grimm from Hanau, Germany. Ordinary

atomic spectroscopy In physics, atomic spectroscopy is the study of the electromagnetic radiation absorbed and emitted by atoms. Since unique elements have unique emission spectra, atomic spectroscopy is applied for determination of elemental compositions. It can ...

can be used to determine the surface of a material, but not its layered structure. In contrast, GDOES gradually

ablate Ablation ( – removal) is the removal or destruction of something from an object by vaporization, chipping, erosive processes, or by other means. Examples of ablative materials are described below, including spacecraft material for ascent and ...

s the layers of the sample, revealing the deeper structure. GDOES spectroscopy can be used for the quantitative and qualitative determination of elements and is therefore a method of

analytical chemistry Analytical skill, Analytical chemistry studies and uses instruments and methods to Separation process, separate, identify, and Quantification (science), quantify matter. In practice, separation, identification or quantification may constitute t ...

Process

The metallic samples are used as a

cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead-acid battery. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. Conventional curren ...

in a direct current plasma. From the surface, the sample is removed in layers by sputtering with argon ions. The removed atoms pass into the plasma by diffusion. Photons are emitted with excited waves and have characteristic wavelengths which are recorded by means of a downstream

spectrometer A spectrometer () is a scientific instrument used to separate and measure Spectrum, spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomeno ...

and subsequently quantified. When using a high-frequency alternating voltage for plasma generation and the corresponding construction of the glow discharge source, non-metallic samples can also be examined. Various instruments are used as sensors.

Photomultiplier A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for sh ...

s can detect the slightest traces and also high concentrations of the sensor-specific element. By means of

charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...

, a complete element spectrum can be measured with the appropriate layer thickness.

Applications

Glow discharge spectroscopy is an established method for the characterization of steels and varnishes. Recent developments relate to the analysis of porous electrodes from lithium-ion batteries.

References

External links

Glow Discharges
Glow Discharge Laboratory

with excellent illustrations {{Branches of spectroscopy Emission spectroscopy

Process

Applications

Further reading

References

External links