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Atomic Absorption Spectroscopy (AAS)I. Mentor : Prof. Kuniyuki KITAGAWA Assistant: Dr. Eng.Nelfa Desmira. Visible and Ultraviolet Light. Uv -Vis Spectrometer Double Beam. Light Source UV (Deuterium/D2). Diffraction Grating. 1a. 2. Mirror 1. Slit 1. 1b.

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atomic absorption spectroscopy aas i

Atomic Absorption Spectroscopy (AAS)I

Mentor :

Prof. Kuniyuki KITAGAWA

Assistant:

Dr. Eng.NelfaDesmira

uv vis spectrometer double beam
Uv-Vis Spectrometer Double Beam

Light Source UV (Deuterium/D2)

Diffraction Grating

1a

2

Mirror 1

Slit 1

1b

Light Source Vis (Tungsten)

Slit 2

3

Detector-2

Filter

I0

Reference

Cuvette

Mirror 4

7a

Reference Beam

6a

Lens 1

Half Mirror

5

4

Detector-1

Mirror 2

Sample

Cuvette

6b

7b

Sample Beam

I

Mirror 3

Lens 2

uv vis spectrometer double beam1
Uv-Vis Spectrometer Double Beam
  • No 1a and 1 b
    • The UV-Visible spectrophotometer uses two light sources, a deuterium (D2) lamp for ultraviolet light and a tungsten (W) lamp for visible light. Two light sources hit Mirror 1 one pass through slit 1 go to diffraction grating (no.2)
  • No 2
    • The grating is able to rotated so a specific wavelength is selectable. From diffraction grating goes to slit 2 and filter (No. 3)
  • No 3
    • A filter is used to remove unwanted higher orders of diffraction.
  • No 4
    • The light beam hits a second mirror
  • No 5
    • splited by a half mirror to 6a and 6b
  • No 6a and 6b
    • Half of the light is reflected (6a), the other half passes through (6b)
  • No 7a
    • One of the beams is allowed to pass through a reference cuvette.
  • No 7b
    • the other passes through the sample cuvette. The intensities of the light beams are then measured at the end
beer lambert law
Beer-Lambert Law
  • The Beer-Lambert law is the linear relationship between absorbance and concentration of an absorbing species.
  • Experimental measurements are usually made in terms of transmittance (T), which is defined as:T = I / Iowhere I is the light intensity after it passes through the sample and Io is the initial light intensity.
  • The relation between A and T is:A = -log T = - log (I / Io)

where A is the measured absorbance

transmittance
Transmittance

The relationship between absorbance and transmittance is illustrated in the following diagram:

assignment
Assignment
  • Calculate the transmission for absorbance A 0.6 and 0.06
  • How to make correction for background absorption caused by sample matrices   using a one-beam spectrophotometer?
  • Explain the system of single beam Uv-Vis Spectrometer
atomic absorption spectroscopy aas ii

Atomic Absorption Spectroscopy(AAS) II

Mentor :

Prof. Kuniyuki Kitagawa

Assistant :

Dr. Eng. NelfaDesmira

atomic spectroscopy
Atomic Spectroscopy
  • A method to analyze the elemental composition using atomic absorption or emission
  • Energy transition electrons of atoms

Absorption

Emission

E1

E1

1

2

3

1

v1

Excited State

Excited State

E2

E2

v2

2

E3

E3

3

v3

E0

Ej

Ground State

Ground State

h = Ei– E0

i = 1.2 and 3

h = Ej – Ei

i = 1.2 and 3

atomic absorption spectroscopy
Atomic Absorption Spectroscopy

Ej

Beer Lambert Law :

I

I0

E0

Where :

A = absorbance/Emission

T = Transmitance

Atomic Absorption Spectroscopy :

The term used when the radiation absorbed by atoms is measured

E0 and Ej : energy levels where Ej higher than E0.

Arrow line: Absorption

atomic absorption spectrometry
Atomic Absorption Spectrometry

Atomized Sample

(Flame)

Lens

Radiation Source

Lens

Monochromator

Detector

Flame Atomic Absorption Spectrometry

AAS consist of two type: Flame AAS and Graphite-furnace AAS.

Please open this link : http://www.cee.vt.edu/ewr/environmental/teach/smprimer/aa/aadiag.gif

Output

atomic absorption spectrometry1
Atomic Absorption Spectrometry
  • Radiation Source
    • Hollow-Cathode Lamp
  • AtomizationSample
    • AAS analyzes atoms in gas phase so atoms in a sample must heated/vaporized in a high-temperature source such as a flame or graphite furnace. Flame AA is suitable to analyze solutions, while graphite furnace AA is able to analyze solutions, slurries, or solid samples.
atomic absorption spectrometry2
Atomic Absorption Spectrometry
  • Monochromator and Detector
    • AA spectrometers use monochromators and detectors for UV and visible light.
    • Monochromator is used to isolate the absorption line from background light due to interferences.
slide14

Assignment

  • Explain the detail of flame atomization absorption spectrometry (FAAS)
  • Explain the detail of graphite furnace atomization absorption spectrometry (GAAS)
  • Compare the detection limits of FAAS and GAAS and mention their applications respectively
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