Principle ofEmission Spectroscopy I

Mentor :Prof. Kuniyuki KITAGAWA

AssistantNelfa Desmira

What is Spectroscopy ?

• Method where interaction of electromagnetic radiation with chemical molecules is measured and visualized in order to obtain characteristics, properties and quantity of an element in one object.

• Electromagnetic radiation has both a particle (photon) and a wave properties. Particles (photons) have a definite mass and they occupy space. Waves have no mass and yet they carry energy as they travel through space.

Your lights shine and your microwave runs and your radio plays because the electromagnetic field exists

RADIATION

Electromagnetic Radiation

Electromagnetic radiation energy radiated in the form of a wave as a result of the motion of electric charges.

Spectroscopy Radiation Terminology

Wavelength ( ) The distance between crests of a waveAmplitude Distance between two peaks (lowest or highest) on the wave and the center of

gravity of the waveWave number (n) The number of waves on a unit of length/distance per cycleFrequency (v) The number of waves per unit of time

Wavelength

WavelengthAmplitude

One oscillation

Radiation Spectrum

The distribution of electromagnetic radiation according to their energy , wavelength, color and frequency

Visible Color for visible Light

Spectroscopy Colors

Light Energy

Spectroscopy Wavelength and Frequency Relation

Where : = wavelength (nm)v = frequency (Hz;/s), c = light velocity (2.998 x 108 m/s)

Spectroscopy as Particle and Wave (The De-Broglie Relationship)

Where : • h = Planck’s constant (6.626068 × 10-34 m2 kg / s)• v = frequency (Hz;/s)

When

Assignment

• Calculate the frequency of red light that has a wavelength of 700.0 nm if the speed of light is 2.998 x 108 m/s.

• Try to investigate and explain some evidences of light as particles (photons) and wave you found.

Principle of Atomic Emission Spectroscopy

(AES) II

Mentor :Prof. Kuniyuki Kitagawa

Assistant :Dr. Eng. Nelfa Desmira

Atomic Emission Spectroscopy

Atomic Emission Spectroscopy : - provides a qualitative and quantitative way of determining analyte concentration by measuring the optical emissions from excited atoms.

Ei and Ej : energy levels where Ej higher (greater energy) than Ei.

Atomic Emission Spectrometry

• Samples are first converted into gas and then excited by flame, electrical discharge (arc or spark), laser, or plasma source depending on operating and measurement criteria.

• As the excited gas atoms return to a relaxed state, energy is released in the form of light which can be separated into characteristic spectral lines by a monochromator.

Atomic Emission Spectrometry

• A variety of excitation sources are described in separate documents: – Direct-current plasma (DCP)– Flame – Inductively-coupled plasma (ICP) – Laser-induced breakdown (LIBS) – Laser-induced plasma – Microwave-induced plasma (MIP) – Spark or arc

Atomic Emission Spectrometry

Direct Current Plasma

• The direct current plasma is created by the electronic release of the two electrodes. The samples are placed on an electrode. In the technique solid samples are placed near the discharge to encourage the emission of the sample by the converted gas atoms.

Flame

A flame provides a high-temperature source for desolvating and vaporizing a sample to obtain free atoms for spectroscopic analysis. In atomic absorption spectroscopy ground state atoms are desired. For atomic emission spectroscopy the flame must also excite the atoms to higher energy levels.

Differences between AAS, AES

Spectrometry Spectrometry

Assignment

Explain the detail of other types of excitation of AES (inductively coupled plasma, laser induced breakdown, laser induced plasma, microwave induced plasma, spark or arc) and explain the advantages of each method respectively