1
SPECTROSCOPY
15.03.2025
.AA
STUDY BY EDUCATOR
CONTEXT
Introduction of spectroscopy.
Electromagnetic radiation and its interaction with matter.
Development of spectroscopic analytical techniques employing various transitions.
Basic introduction to atomic and molecular spectroscopic techniques
Include:
● Flame emission spectrophotometry.
● UV/VIS and IR spectroscopies.
, 2
Spectroscopy
Spectroscopy is the study of the interaction between light (electromagnetic radiation) and
matter.
The matter can be atoms, ions, and molecules.
It helps identify substances and analyze their composition based on how they absorb, emit, or
scatter electromagnetic radiation.
It is widely used in chemistry, physics, astronomy, and medicine.
Spectrometer
is an instrument which can be used to measure the presence of a particular compound or
particle in a molecule.
SPECTRUM
Spectrum is a plot of the amount of light absorbed by a sample versus the wavelength of the
light.
A spectrum is the range of different wavelengths of electromagnetic radiation emitted, absorbed,
or scattered by a substance. It can be continuous (like a rainbow), discrete (line spectra from
atoms), or band spectra (from molecules). Spectra are used in various scientific fields to analyze
materials and their properties.
The amount of light absorbed is called absorbance.
Frequency:Frequency is the number of wave cycles that pass a point per second, measured in
hertz (Hz). It is a fundamental property of waves, including sound, light, and electromagnetic
radiation. In spectroscopy, frequency is related to energy and wavelength by the equation ν = c/λ,
where ν is frequency, c is the speed of light, and λ is wavelength.
Wavelength:Wavelength is the distance between two consecutive peaks or troughs of a wave,
usually measured in meters (m), nanometers (nm), or angstroms (Å). It is inversely related to
frequency: shorter wavelengths have higher frequencies and energy (e.g., X-rays), while longer
wavelengths have lower frequencies and energy (e.g., radio waves). Wavelength is crucial in
spectroscopy for identifying substances based on their interaction with electromagnetic
radiation.
Amplitude:Amplitude is the maximum displacement of a wave from its equilibrium position. It
represents the wave's intensity or strength—higher amplitude means greater energy. In
spectroscopy, amplitude affects the intensity of absorbed or emitted light, helping to determine
concentration and properties of substances.
ENERGY ∝FREQUENCY∝WAVENUMBER ∝1/WAVELENGTH.
, 3
THz 480 510 540 610 670 750 frequency
nm 635 590 560 490 450 400 wavelength
Low frequency and High frequency
Low Frequency and High Frequency refer to the number of wave cycles per second:
Low Frequency: Waves with fewer cycles per second (longer wavelength, lower energy).
Examples: Radio waves, microwaves.
High Frequency: Waves with more
cycles per second (shorter wavelength,
higher energy). Examples: X-rays,
gamma rays.
In spectroscopy, higher frequency
radiation interacts differently with
matter, often leading to more energetic
transitions.
Electromagnetic radiation
EM is the form of energy that is all
around us.
And has both electrical and magnetic characteristics.
The study of electromagnetism deals with how electrically charged particles interact with each
other and with magnetic fields.
Electromagnetic radiation is also the form of energy and has both electrical and magnetic
characteristics.
The electric and magnetic fields in nth electromagnetics wave oscillate along directions
perpendicular to the propagation direction of the wave .
Comparison between electric ,vibrational and rotational transition
Following as shown;
1. Nature of Transition
Electronic Transition:
Involves the movement of electrons between different energy levels or orbitals in a
molecule.
SPECTROSCOPY
15.03.2025
.AA
STUDY BY EDUCATOR
CONTEXT
Introduction of spectroscopy.
Electromagnetic radiation and its interaction with matter.
Development of spectroscopic analytical techniques employing various transitions.
Basic introduction to atomic and molecular spectroscopic techniques
Include:
● Flame emission spectrophotometry.
● UV/VIS and IR spectroscopies.
, 2
Spectroscopy
Spectroscopy is the study of the interaction between light (electromagnetic radiation) and
matter.
The matter can be atoms, ions, and molecules.
It helps identify substances and analyze their composition based on how they absorb, emit, or
scatter electromagnetic radiation.
It is widely used in chemistry, physics, astronomy, and medicine.
Spectrometer
is an instrument which can be used to measure the presence of a particular compound or
particle in a molecule.
SPECTRUM
Spectrum is a plot of the amount of light absorbed by a sample versus the wavelength of the
light.
A spectrum is the range of different wavelengths of electromagnetic radiation emitted, absorbed,
or scattered by a substance. It can be continuous (like a rainbow), discrete (line spectra from
atoms), or band spectra (from molecules). Spectra are used in various scientific fields to analyze
materials and their properties.
The amount of light absorbed is called absorbance.
Frequency:Frequency is the number of wave cycles that pass a point per second, measured in
hertz (Hz). It is a fundamental property of waves, including sound, light, and electromagnetic
radiation. In spectroscopy, frequency is related to energy and wavelength by the equation ν = c/λ,
where ν is frequency, c is the speed of light, and λ is wavelength.
Wavelength:Wavelength is the distance between two consecutive peaks or troughs of a wave,
usually measured in meters (m), nanometers (nm), or angstroms (Å). It is inversely related to
frequency: shorter wavelengths have higher frequencies and energy (e.g., X-rays), while longer
wavelengths have lower frequencies and energy (e.g., radio waves). Wavelength is crucial in
spectroscopy for identifying substances based on their interaction with electromagnetic
radiation.
Amplitude:Amplitude is the maximum displacement of a wave from its equilibrium position. It
represents the wave's intensity or strength—higher amplitude means greater energy. In
spectroscopy, amplitude affects the intensity of absorbed or emitted light, helping to determine
concentration and properties of substances.
ENERGY ∝FREQUENCY∝WAVENUMBER ∝1/WAVELENGTH.
, 3
THz 480 510 540 610 670 750 frequency
nm 635 590 560 490 450 400 wavelength
Low frequency and High frequency
Low Frequency and High Frequency refer to the number of wave cycles per second:
Low Frequency: Waves with fewer cycles per second (longer wavelength, lower energy).
Examples: Radio waves, microwaves.
High Frequency: Waves with more
cycles per second (shorter wavelength,
higher energy). Examples: X-rays,
gamma rays.
In spectroscopy, higher frequency
radiation interacts differently with
matter, often leading to more energetic
transitions.
Electromagnetic radiation
EM is the form of energy that is all
around us.
And has both electrical and magnetic characteristics.
The study of electromagnetism deals with how electrically charged particles interact with each
other and with magnetic fields.
Electromagnetic radiation is also the form of energy and has both electrical and magnetic
characteristics.
The electric and magnetic fields in nth electromagnetics wave oscillate along directions
perpendicular to the propagation direction of the wave .
Comparison between electric ,vibrational and rotational transition
Following as shown;
1. Nature of Transition
Electronic Transition:
Involves the movement of electrons between different energy levels or orbitals in a
molecule.
