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

ספקטרופוטומטר בליעה אטומי מורכב ממקור קרינה, אטומייזר, מונוכרומטור וגלאי.
למקור הקרינה יש בדרך כלל טווח צר, כמו מנורה קתודית חלולה, או HCL, או מנורת פריקה ללא אלקטרודות, או EDL. מכשירים עם מקורות רצף משתמשים מונוכרומטורים ברזולוציה גבוהה מאוד.
הבא בתור הוא האטומיזר, כאשר השיטות הנפוצות הן אטומיזציה של להבה ואטומיזציה אלקטרותרמית. 
חלק מהאטומים מעוררים תרמית ופולטים קרינה. ניתן לבודד הפרעה זו על ידי שימוש במסוק מכני בין המקור לאטומיזר כדי לתת לפליטות הנגרמות על ידי קרינת המקור תבנית ברורה בתדר קבוע.
בספקטרופוטומטר של קרן אחת, הקרינה עוברת ישירות דרך הדגימה האטומית.
מכשיר בעל אלומה כפולה מפצל את קרן המקור. קרן אחת עוברת דרך הדגימה האטומית, ואילו השנייה עוקפת אותה. לאחר מכן, שתי הקורות מתחברות מחדש באמצעות מראה חצי כסופה.
לאחר מכן, הקרן עוברת דרך המונוכרומטור, אשר שולח רק טווח אורכי גל צר לגלאי – בדרך כלל, צינור מכפיל אור, אשר ממיר אור לאותות חשמליים מוגברת.

ספקטרוסקופיית ספיגת אטומים: מכשור

Atomic Absorption Spectroscopy: Instrumentation

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ספקטרופוטומטר ספיגת אטומים (AAS) מורכב ממספר רכיבים: מקור קרינה, אטומייזר, מונוכרומטור וגלאי. מקור הקרינה יכול להיות מנורת קתודה חלולה (HCL) או מנורת פריקה חסרת אלקטרודות (EDL), המספקות קו פליטה צר באורך הגל הנדרש. עם זאת, מכשירים מסוימים משתמשים במקורות רציפים ובמונוכרומטורים ברזולוציה גבוהה כדי להשיג טווח קרינה צר.

האטומייזר המשמש ב-AAS יכול להיות אטומייזר להבה או אטומייזר אלקטרותרמי. האטומים במצב גזי הנוצרים על ידי האטומייזר עוברים לעיתים עירור תרמי ופולטים קרינה, דבר שגורם להפרעה לאות מקור הקרינה. דיסק מתכת עגול, המכונה צ'ופר, משמש לביטול הפרעה זו בין מקור הקרינה לאטומייזר הלהבה. הצ'ופר המתכתי מבודד את מקור הקרינה על ידי יצירת אות משתנה, בניגוד לאות הרציף מהלהבה.

בספקטרופוטומטר קרן יחידה, הקרינה עוברת ישירות דרך הדגימה האטומית, בעוד שבמכשיר קרן כפולה, קרן המקור מתחלקת, כאשר קרן אחת עוברת דרך הדגימה האטומית והקרן השנייה היא קרן הייחוס. שתי הקרניים משולבות מחדש באמצעות מראה חצי-מוכספת. הקרן המשולבת עוברת לאחר מכן דרך המונוכרומטור, אשר מאפשר לטווח צר של אורך גל להגיע לגלאי. הגלאי הוא בדרך כלל שפופרת מַכְפֵּלוֹר המעבדת וממירה את הקרינה לאותות חשמליים מוגברים.
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ספקטרופוטומטר בליעה אטומי (AAS) מורכב ממספר מרכיבים: מקור קרינה, אטומייזר, מונוכרומטור וגלאי. הקרינה ...

atomic-absorption-spectroscopy-instrumentation

Education

JoVE Core

Analytical Chemistry

כימיה אנליטית

Unit 1

יחידה 1

Atomic Spectroscopy

ספקטרוסקופיה אטומית

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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

atomic spectroscopy: absorption, emission, and fluorescence

atomic-spectroscopy-absorption-emission-and-fluorescence

Element Analysis with Atomic Light Spectra

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...

atomic spectroscopy: effects of temperature

atomic-spectroscopy-effects-of-temperature

How Heat Changes Atomic Spectra

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

Atomic absorption spectroscopy uses sample atomization to turn a liquid specimen into free atoms for analysis. The two main approaches are flame atomization and electrothermal atomization. Both methods prepare the sample so its atoms can be measured by the instrument. Flame atomization uses a nebulizer and spray chamber to mix the sample with a fuel-oxidant mixture. This creates a fine aerosol mist that enters the burner. The fuel and oxidant are usually close to a stoichiometric ratio, but a...

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

Atomic absorption spectroscopy (AAS) depends on careful sample preparation and calibration. Samples must be turned into clear solutions before measurement. That often means extra treatment to dissolve materials such as soils, animal tissues, and minerals. Common sample prep methods include hot mineral acids, wet ashing, combustion in closed containers, high-temperature ashing, and fusion with reagents. These steps help make the sample suitable for AAS analysis. Solutions that contain organic...

atomic emission spectroscopy: overview

Atomic Emission Spectroscopy for Element Analysis

Atomic emission spectroscopy is used to identify the elements in a sample by measuring the light they emit. Atoms are first excited to higher energy levels by thermal energy from hot sources such as plasma, arcs, or sparks. When they fall back to lower energy levels, they give off light at specific wavelengths. Each element produces its own set of lines, so the emission spectrum can show both what is present and how much is there. AES instruments are similar to atomic absorption spectrometers,...

atomic emission spectroscopy: instrumentation

atomic-emission-spectroscopy-instrumentation

AES Sample Handling and Detection

Atomic emission spectrometry (AES) uses sample handling, atomization, and detection parts to measure emitted light from atoms and ions. The sample must first be changed into a gas-phase form so it can produce a measurable signal. AES uses two main atomizer types. Continuous atomizers, such as flames and plasmas, feed the sample in a steady stream. Discrete atomizers add one sample at a time with syringes or autosamplers. The electrothermal atomizer is the most common discrete type. Many...

atomic emission spectroscopy: interference

atomic-emission-spectroscopy-interference

Reducing Interference in AES Signals

Atomic emission spectroscopy (AES) can produce interfering signals when atoms and molecules in a flame or plasma emit overlapping light. High-temperature atomizers excite many species at once, including oxides, hydroxides, and flame combustion products. These extra emissions can make the analyte signal harder to read. Spectral interference happens when emission lines or bands overlap. One way to reduce it is to improve instrument resolution. Another is to choose a different emission line for...

inductively coupled plasma atomic emission spectroscopy: principle

inductively-coupled-plasma-atomic-emission-spectroscopy-principle

ICP-AES Torch and Sample Analysis

Inductively coupled plasma atomic emission spectroscopy uses a plasma torch to analyze elements in a sample. This method is also called inductively coupled plasma optical emission spectroscopy, or ICP-OES. It is widely used because the plasma creates a strong environment for elemental analysis. The ICP source, or torch, contains three concentric quartz tubes. Argon gas flows through the tubes. A spark from a Tesla coil starts the ionization of argon and creates a high-temperature plasma. The...

inductively coupled plasma atomic emission spectroscopy: instrumentation

inductively-coupled-plasma-atomic-emission-spectroscopy

ICP-AES Instrument Types and Detection

Inductively coupled plasma atomic emission spectroscopy, or ICP-AES, uses an inductively coupled plasma to detect and analyze elements in a sample. The method measures the light given off by atoms, which helps identify and compare different elements. It is a common approach in atomic emission spectroscopy. ICP-AES instruments are built in three main forms: sequential, simultaneous multichannel, and Fourier transform instruments. Fourier transform designs are less commonly used, but they are...

atomic emission spectroscopy: lab

Plasma Sources in Atomic Emission Spectroscopy

Atomic emission spectroscopy uses plasma sources to identify elements by their light. The method creates abundant spectra with characteristic emission lines. Inductively coupled plasma, or ICP, is especially useful because it gives strong quantitative data. It works well under stable conditions, with low noise, low background, and few interferences. Newer air-operated microwave sources are also being studied. These sources may be more cost-effective than conventional ICP systems. Atomic...

atomic fluorescence spectroscopy

Measuring Elements by Atomic Fluorescence

Atomic fluorescence spectroscopy measures elements by detecting the light atoms give off after they are excited by electromagnetic radiation. The atoms are first placed in a flame, furnace, or plasma. They absorb energy, become excited, and then release that energy as they return to their original state. The emitted light is called fluorescence. The fluorescence is observed at a right angle to the incoming beam. This setup helps separate the emitted light from the light used to excite the...

flame photometry: overview

Flame Emission Spectrometry Basics

Flame emission spectrometry uses a flame to excite elements in a sample so their light can be measured. It is also called flame photometry. The method can be used for both qualitative and quantitative analysis of elements. The idea became established in the early 1860s when Kirchhoff and Bunsen showed that specific elements give off characteristic radiation in a flame. The first instrument for this purpose measured sodium in plant ash with a Bunsen flame. A major problem was how to add the...

flame photometry: lab

Flame Photometry and Metal Detection

Flame photometry is a method for detecting metals by measuring the light they emit in a flame. A solution such as potassium chloride is aspirated into the flame. The solvent evaporates first. The remaining salt becomes dehydrated and then dissociates into free gaseous atoms in the ground state. Some of these atoms absorb energy from the flame and move to an excited state. When they return to the ground state, they emit photons at characteristic wavelengths. These emissions are very narrow...

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

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Atomic Absorption Spectroscopy: Key Parts

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