EMISSION AND ABSORPTION SPECTRUM

Two main types of spectra exist, emission spectra and absorption spectra. Emission spectra involve electrons moving from lower to higher energy levels, which occurs when they take in energy. These excited electrons must then release, or emit, this energy to return to their ground states. The frequencies of this emitted light comprise their emission spectrum. 

Absorption spectra, in contrast, concern light frequencies of electrons that absorb energy. These electrons move from their ground states to higher energy states. The frequencies of this absorbed light comprise their absorption spectrum.

THEORY

What is Emission Spectrum?

When energy is absorbed by electrons of an atom, electrons move from lower energy levels to higher energy levels. These excited electrons have to radiate energy to return to ground states from the excited state, which is unstable. The emission spectrum is formed by the frequencies of these emitted light.

What is Absorption Spectrum?

On the other hand, an absorption spectrum is constituted by the frequencies of light transmitted with dark bands when energy is absorbed by the electrons in the ground state to reach higher energy states.

Spectrum

Waves of all radiation in the visible range make up ordinary white light. This is why, when white light goes through a prism, it appears as a spectrum of coloured bands.

We call it a continuous spectrum because the colours blend together, such as violet blending into blue, blue blending into green, and so on. When this light passes through an item or medium, the wavelength with the shortest wavelength (violet) deviates the most from the wavelength with the longest wavelength (red) (red).

Electromagnetic radiation interacts with matter, causing atoms and molecules to absorb energy and transition to a higher energy state. They must emit radiation to return to their regular states because this state is unstable.

Spectrum of Emissions

1. When electromagnetic radiation interacts with atoms or molecules of matter, the electrons in these atoms absorb energy and move to a higher energy state, causing them to lose their stability.
2. They must go from the higher energy level to the prior lower energy state in order to reestablish their stability.
3. These atoms and molecules use radiation from various parts of the electromagnetic spectrum to accomplish their goals.
4. An emission spectrum is the range of radiation released by electrons in excited atoms or molecules.

Spectrum of Absorption

1. When a ray of white light strikes a prism, it is refracted twice, as we can see.
2. It does this twice: once when it goes from a rarer medium (air) to a denser medium (glass), and then again when it travels from a denser medium (glass) to a rarer medium (air) (air).
3. Finally, we see a spectrum, which is a band of colours created by a ray of white light. When we look at this spectrum more closely, we can see that the colour with the shortest wavelength deviates the most, and vice versa.
4. As a result, a spectrum of choices rather than solely from red to violet can be seen, with red suffering the least variation due to its longest wavelength.
5. As violet merges become blue, blue into green, and so on, this type of spectrum is referred to as a continuous spectrum.

Spectra of Emission and Absorption

The spectrum of radiation released by a substance that really has absorbed energy is known as the emission spectrum. Excited atoms, molecules, and ions are those that have absorbed radiation. The emission spectrum is the inverse of the absorption spectrum.

It is the spectrum created by electromagnetic radiation passing through a medium in which some frequencies are absorbed. The study of fluorescence and absorption spectra is known as spectroscopy.

Spectrum of Lines

The emission spectra of electrons in the gas phase produce light exclusively at certain wavelengths with dark intervals between them, unlike visible light, which has a continuous spectrum of all wavelengths. The emitted radiation is identified by bright lines in the spectra, which are referred to as line spectra or atomic spectra.

Spectrums of Emission and Absorption

1. A photograph negative of such an emission spectrum is an absorption spectrum.
2. Electromagnetic radiation is bombarded on a sample that absorbs radiation of specific wavelengths in order to observe the absorption spectrum.
3. The wavelength of radiation absorbed by matter contributes to the missing wavelength, resulting in dark spots in the otherwise bright continuous spectrum.
4. Each element has its own spectrum of line emission. Spectroscopy is the study of the emission lines or the absorption spectrum.

Main Difference – Absorption vs Emission Spectra

The structure of an atom includes a central core called a nucleus and a cloud of electrons around the nucleus. According to modern atomic theory, these electrons are positioned in specific energy levels called shells or orbitals where their energies are quantized. The shell which is the nearest to the nucleus is known to have the lowest energy. When energy is given to an atom externally, it causes the electrons to jump from one shell to another. These movements can be used to obtain absorption and emission spectra. Both absorption and emission spectra are line spectra. The main difference between absorption and emission spectra is that absorption spectra show black colored gaps/lines whereas emission spectra show different colored lines in the spectra.

 How are emission and absorption spectra similar

Light Absorption by Hydrogen

The hydrogen atom is a relatively basic atom. It has a single proton in its nucleus and one electron orbiting around it. The lowest energy level of a hydrogen atom’s electron is when it is just sitting about without much energy. The electron in the atom moves to a higher energy level (an “excited state”) when it absorbs light. Depending on how much energy it absorbs, it can jump one or several levels.

The electron can only go from one energy level to the next, which is fascinating. It can’t switch levels halfway. Furthermore, moving an electron from one level to another requires a precise quantity of energy—no more, no less.

The amount of energy required for an electron to jump to a higher level corresponds toward the wavelength of light it absorbs. To put it another way, electrons only absorb photons that provide them with the exact amount of energy they require to leap levels.

The results of this interaction can be seen in the absorption spectra of hydrogen. Hydrogen absorbing light spectrum of 410 nm (violet), 434 nm (blue), 486 nm (blue-green), and 656 nm (blue-green) in the visible spectrum (red). Each of the absorption lines represents a different electron leap. The electron jumps four levels when exposed to the shortest frequency range energy light (violet 410 nm), but only one level when exposed to the longest light spectrum energy light (red 656 nm).

Light Emission by Hydrogen

The wavelength of light an electron absorbs corresponds to the amount of energy required for it to leap to a higher level. To put it another way, electrons only absorb photons that contain the exact amount of energy they need to leap levels.

The absorption bands of hydrogen show the outcomes of this interaction. In the visible spectrum, hydrogen absorbs light at wavelengths of 410 nm (violet), 434 nm (blue), 486 nm (blue-green), and 656 nm (blue-green) (red). Each absorption line corresponds to a different electron jump. When exposed to the smallest frequency bandwidth vitality light (violet 410 nm), the electron leaps four levels, but only one level when exposed towards the longest light spectra energy light (red 656 nm).

CONCLUSION

A spectrum obtained from electromagnetic energy transmitted throughout a gas or any solid is referred to as an absorption spectrum. When atoms absorb energy, they produce an emission spectrum. Both absorption and emission spectra are line spectra. The main difference between absorption and emission spectra is that absorption spectra show black colored gaps/lines whereas emission spectra show different colored lines in the spectra.