14.10

Atomic Emission Spectroscopy: Instrumentation

1.7K views01:22 min

The atomic emission spectrometer comprises a sample nebulizer, a plasma source, a wavelength-isolating device, transducers, and a microprocessor controller.

The sample is drawn using a peristaltic pump and transported to a nebulizer, which converts the sample solution into fine droplets.

Larger droplets are directed to a drain, while the fine droplets are carried by argon gas to the plasma—commonly, direct current plasma or inductively coupled plasma.

In the plasma, the samples are atomized to gas-phase atoms and ions and, on further collision, get excited.

The atomic or ionic emission from the plasma is then separated by a monochromator, polychromator, or spectrograph.

Monochromators separate individual wavelengths sequentially through a single exit slit, whereas polychromators with several exit slits isolate multiple wavelengths concurrently.

Alternatively, a spectrograph enables a range of wavelengths to be monitored simultaneously.

The isolated radiation is converted into electrical signals by single or multiple photomultiplier transducers or array detectors and is further analyzed.

Overview

Loading...

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

The instrumentation of atomic emission spectrometry (AES) involves various components, including atomization devices that convert samples into gas-phase atoms and ions. There are two main types of atomization devices: continuous and discrete atomizers. Continuous atomizers, like plasmas and flames, introduce samples in a constant stream, while discrete atomizers inject individual samples using syringes or autosamplers. The most common discrete atomizer is the electrothermal atomizer.

Nebulization is the process of introducing samples in the form of aerosols. A nebulizer generates a fine spray of droplets from the liquid sample, allowing efficient atomization. Once atomized, the sample in a flame or plasma forms a steady-state population of atoms, molecules, and ions. The emission from the plasma is then separated into constituent wavelengths using a wavelength isolation device, such as a monochromator, polychromator, or spectrograph. The isolated radiation is converted into electrical signals by transducers or array detectors, which are then processed and analyzed by computer systems.

Inductively coupled plasma (ICP) emission systems utilize a high-temperature plasma called an argon plasma torch instead of a flame. This enables a broader application and rapid multi-element analysis. In the direct-current plasma source (DCP), heating of inert gas is achieved through a DC-arc, establishing the plasma in a high-velocity gas stream. The DCP design commonly uses an inverted V-shaped electrode assembly with the excitation region at the intersection of argon streams, and a nebulizer is employed to inject the sample at this point.

Different instruments are available for multi-element determinations, including sequential spectrometers that scan different emission lines in sequence and simultaneous spectrometers that use polychromators or spectrographs to measure multiple wavelengths simultaneously. The instrumentation of atomic emission spectrometry offers different optical path options, including sequential optical paths with monochromators for sequential wavelength measurement and simultaneous direct reading polychromators with multiple exit slits and phototubes for simultaneous measurement of multiple emission lines.

Transcript

Explore More Videos

Atomic Emission Spectroscopy

Atomization Devices

Continuous Atomizers

Discrete Atomizers

Nebulization Process

Electrothermal Atomizer

Wavelength Isolation

Monochromator Polychromator

Inductively Coupled Plasma

Direct Current Plasma