Inductively Coupled Plasma Atomic Emission Spectroscopy: Instrumentation

Plasma emission spectroscopy uses three basic instrument types.

Sequential plasma emission spectrometers measure one emission line at a time, whereas multichannel and Fourier-transform instruments simultaneously measure multiple emission lines.

Sequential spectrometers typically use a grating monochromator, where the grating is rotated to focus different wavelengths on the exit slit.

For example, in slew scan spectrometers, the monochromator rapidly rotates to a wavelength close to one emission line and then rotates in small steps across that line.

In contrast, scanning echelle spectrometers have a moving photomultiplier tube behind an aperture plate, with the echelle grating scattering the wavelengths in a broad array that can be detected one slit at a time.

Some multichannel instruments use a grating polychromator to measure multiple emission lines simultaneously with photomultiplier tubes positioned behind fixed exit slits.

Other multichannel instruments use spectrographs for simultaneous measurements, employing two-dimensional charge-injection devices or charge-coupled devices as transducers.

Although Fourier transform spectrometers offer wide wavelength coverage, they are not widely used in AES due to their various limitations.