The electromagnetic spectrum is a long-range series of all electromagnetic waves that arranged according to frequency and wavelength. The sun, stars, clusters, earth, and other bodies radiate electromagnetic radiation having different wavelengths. Electromagnetic waves pass through space at the speed of the light in the form of sinusoidal waves.
Types of the electromagnetic spectrum
The electromagnetic spectrum is categorized into three different categories. They categorized with respect to their properties or physical behavior that they show when they pass through different mediums.
A continuous spectrum might be white light, but it is only a part of the electromagnetic spectrum. There are many wavelengths than we can see with our human eyes. The continuous spectrum includes ultraviolet, radio waves, X-rays, microwaves and infrared and gamma rays.
A continuous spectrum is produced by solids, liquids & dense gases produce – no “gaps” in wavelength of light produced:
The emission spectrum of a chemical compound or chemical element is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state. Each element emission spectrum is unique and have specific properties.
The emission spectrum is produced by rarefied gases – emission only in narrow wavelength regions:
The absorption of electromagnetic radiation is how matter takes up a photon’s energy. This means that the typical electrons bound in atoms. These atoms transform electromagnetic energy into the internal energy of the absorber (like thermal energy). This effect gradually reduces the intensity of the light waves as they propagate through a medium. Also, the absorption of the waves does not depend on their intensity (linear absorption), in certain conditions the medium’s transparency changes by a factor that varies as a function of wave intensity, and saturation absorption (or nonlinear absorption) occurs.
Absorption spectrum Gas atoms absorb the same wavelengths as they usually emit and results in an absorption line spectrum:
- Inline spectrum the Electron transition takes place between energy levels in this result the emission or absorption lines formed.
- Different elements produce different spectra because different elements have different atomic structures.
Emission/Absorption of Radiation by Atoms
EMISSION/ABSORPTION LINES ARE DUE TO RADIATIVE TRANSITIONS:
Radiative (or Stimulated) absorption:
A photon with energy (Eg = hn = E2 – E1) excites an electron from lower energy levels. This means that the electron in the lower orbit gain energy and become excited and jump in the high energy orbit.
This can only occur if Eg = hn = E2 – E1
Types of Radiative recombination
In spontaneous emission, the electron minimizes its total energy by emitting a photon and making the transition from E2 to E1.
Emitted photon has energy Eg’ = hn’ = E2 – E1
stimulated emission photon is strongly coupled with the electron, causing an electron to decay to lower energy level, releasing a photon of the same energy.
Can only occur if Eg = hn = E2 – E1 Also, hn’ = hn
Electron makes the transition to lower energy level (hn’ = E2 – E1) and emits a photon with energy. In this, the electron loses energy in the form of photon and jumps from high level orbital to the low level orbital.
hn’ = E2 – E1