Name: atomic absorption spectroscopy: key parts
Uploaded: 2025-05-22T09:06:10.000Z
Duration: 1 min 22 s
Channel: JoVE

Un spectrophotomètre d’absorption atomique se compose d’une source de rayonnement, d’un atomiseur, d’un monochromateur et d’un détecteur.
La source de rayonnement a généralement une plage étroite, comme une lampe à cathode creuse, ou HCL, ou une lampe à décharge sans électrode, ou EDL. Les instruments à sources continues utilisent des monochromateurs à très haute résolution.
Vient ensuite l’atomiseur, les méthodes courantes étant l’atomisation à la flamme et l’atomisation électrothermique. 
Certains atomes sont excités thermiquement et émettent des radiations. Cette interférence peut être isolée à l’aide d’un hacheur mécanique entre la source et l’atomiseur pour donner aux émissions causées par le rayonnement source un modèle de fréquence distinct et constant.
Dans un spectrophotomètre à faisceau unique, le rayonnement traverse directement l’échantillon atomisé.
Un instrument à double faisceau divise le faisceau source. Un faisceau traverse l’échantillon atomisé, tandis que l’autre le contourne. Ensuite, les deux faisceaux se recombinent à l’aide d’un miroir à moitié argenté.
Ensuite, le faisceau passe à travers le monochromateur, qui n’envoie qu’une gamme de longueurs d’onde étroite au détecteur, généralement un tube photomultiplicateur, qui convertit la lumière en signaux électriques amplifiés.

spectroscopie d'absorption atomique: instrumentation

Atomic Absorption Spectroscopy: Instrumentation

Un spectrophotomètre d'absorption atomique (SAA) comprend plusieurs composants: une source de rayonnement, un atomiseur, un monochromateur et un détecteur. La source de rayonnement peut être une lampe à cathode creuse (HCL) ou une lampe à décharge sans électrode (EDL), qui fournissent toutes deux une ligne d'émission étroite de la longueur d'onde requise. Cependant, certains instruments utilisent des sources continues et des monochromateurs à haute résolution pour obtenir une plage de rayonnement étroite.

L'atomiseur utilisé dans la SAA peut être soit un atomiseur à flamme, soit un atomiseur électrothermique. Les atomes en phase gazeuse générés par l'atomiseur sont souvent excités thermiquement et émettent un rayonnement, provoquant une interférence avec le signal de la source de rayonnement. Un disque métallique circulaire, appelé hacheur, est utilisé pour éliminer cette interférence entre la source de rayonnement et l'atomiseur à flamme. Le hacheur métallique isole la source de rayonnement en créant un signal alternatif, contrairement au signal continu de la flamme.

Dans un spectrophotomètre à faisceau unique, le rayonnement traverse directement l'échantillon atomisé, tandis que dans un instrument à double faisceau, le faisceau source est divisé, un faisceau traversant l'échantillon atomisé et l'autre étant le faisceau de référence. Les deux faisceaux sont ensuite recombinés à l'aide d'un miroir semi-argenté. Le faisceau combiné traverse ensuite le monochromateur, qui ne laisse passer qu'une gamme étroite de longueurs d'onde jusqu'au détecteur. Le détecteur est généralement un tube photomultiplicateur qui traite et convertit le rayonnement en signaux électriques amplifiés.

Spectroscopie d'absorption atomique: instrumentation

Un spectrophotomètre d’absorption atomique (AAS) comprend plusieurs composants : une source de rayonnement, un atomiseur, un monochromateur et un détecteur. Les radiations ...

atomic-absorption-spectroscopy-instrumentation

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Analytical Chemistry

Chimie analytique

Unit 1

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Atomic Spectroscopy

Spectroscopie atomique

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atomic absorption spectroscopy: key parts

Atomic absorption spectrophotometry uses a set of key parts to measure light absorbed by atoms. The main components are a radiation source, an atomizer, a monochromator, and a detector. Each part has a specific job in the instrument.

The radiation source is usually a hollow-cathode lamp, or HCL, or an electrodeless-discharge lamp, or EDL. Both produce a narrow emission line at the needed wavelength. Some instruments instead use continuum sources with high-resolution monochromators to narrow the radiation range.

The atomizer turns the sample into gas-phase atoms. It can be a flame atomizer or an electrothermal atomizer. At times, these hot atoms also emit radiation, which can interfere with the signal from the radiation source.

A circular metal disk called a chopper helps reduce that interference with a flame atomizer. The chopper makes the source beam into an alternating signal. This is different from the continuous signal from the flame.

AAS instruments can also be single-beam or double-beam systems. In a single-beam spectrophotometer, the radiation passes directly through the atomized sample. In a double-beam instrument, the source beam splits into a sample beam and a reference beam, and a half-silvered mirror recombines them.

After recombination, the beam passes through the monochromator. The monochromator allows only a narrow wavelength range to reach the detector. The detector is usually a photomultiplier tube, which converts the radiation into amplified electrical signals.

Atomic Absorption Spectroscopy: Key Parts

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Atomic spectroscopy is used to identify and measure elements by their light signals. It supports both qualitative analysis, which tells what is present, and quantitative analysis, which tells how much is present. The optical methods in this group are atomic absorption spectroscopy, atomic emission spectroscopy, and atomic fluorescence spectroscopy. These methods begin with atomization. In this step, a solid, liquid, or solution sample is changed into gas-phase atoms and ions. Once the sample...

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Heat changes atomic spectra by affecting atomization, excitation, ionization, and line shape. In atomic spectroscopy, atomization means converting a sample into gas-phase atoms and ions. The flame temperature needed for this step changes how efficiently the method works and shifts the balance between excited and ground-state atoms. At thermal equilibrium, the relative numbers of excited and ground-state atoms can be estimated with the Maxwell-Boltzmann distribution. A small temperature rise...

atomic absorption spectroscopy: overview

Atomic Absorption Spectroscopy for Trace Metals

Atomic absorption spectroscopy (AAS) measures trace metals by tracking how atoms absorb electromagnetic radiation (EMR). The absorbed light makes atoms move to a higher-energy orbit. In AAS, the key step is atomization, which converts the sample into gas-phase atoms. A flame or a furnace is typically used for this step. Inside the flame, some atoms become thermally excited. Most stay in the ground state, which is the lowest-energy state. These ground-state gas-phase atoms absorb EMR only when...

atomic absorption spectroscopy: instrumentation

Atomic absorption spectrophotometry uses a set of key parts to measure light absorbed by atoms. The main components are a radiation source, an atomizer, a monochromator, and a detector. Each part has a specific job in the instrument. The radiation source is usually a hollow-cathode lamp, or HCL, or an electrodeless-discharge lamp, or EDL. Both produce a narrow emission line at the needed wavelength. Some instruments instead use continuum sources with high-resolution monochromators to narrow...

atomic absorption spectroscopy: radiation and light sources

atomic-absorption-spectroscopy-radiation-and-light-sources

Choosing Light Sources for AAS Measurements

Atomic absorption spectroscopy (AAS) uses a light source that emits a very narrow range of wavelengths. This is needed because the source must match the absorption behavior of the analyte atom. The choice of source also depends on giving a precise, intense emission at the right wavelength for accurate detection. Two common line sources in AAS are hollow-cathode lamps (HCLs) and electrodeless-discharge lamps (EDLs). These lamps are selected based on the element being analyzed and the level of...

atomic absorption spectroscopy: atomization methods

atomic-absorption-spectroscopy-atomization-methods

Atomic Absorption Spectroscopy: Sample Atomization

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atomic absorption spectroscopy: interference

atomic-absorption-spectroscopy-interference

Correcting Errors in Atomic Absorption Spectroscopy

Atomic absorption spectroscopy interference can create systematic error by making the analytical signal or the background look stronger or weaker than it should be. In atomic absorption measurements, these errors are usually grouped as spectral interference, chemical interference, and physical interference. Spectral interference happens when signals from other elements or molecules overlap with the analyte signal, the substance being measured. This overlap can falsely raise or hide the analyte...

atomic absorption spectroscopy: lab

AAS Sample Prep and Calibration

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atomic emission spectroscopy: overview

Atomic Emission Spectroscopy for Element Analysis

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atomic-emission-spectroscopy-instrumentation

AES Sample Handling and Detection

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atomic-emission-spectroscopy-interference

Reducing Interference in AES Signals

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inductively coupled plasma atomic emission spectroscopy: instrumentation

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Flame Photometry and Metal Detection

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key terms and concepts

Learn the main parts of an atomic absorption spectrophotometer, including the lamp, atomizer, chopper, monochromator, and detector, in clear high school terms.

Atomic Absorption Spectroscopy: Key Parts | JoVE K12

analytical chemistry

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Atomic Absorption Spectroscopy: Key Parts

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