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Light Energy Absorption

Introduction

Light is a form of energy. Basically, it consists of small particles known as “photons”. Photons have two different natures either them act like particles or they behave like waves too. Not only light energy consists of photons but other rays include like X-rays, ultraviolet rays also consist of photons. The difference between this radiation and light is the wavelength (Carr, 2017).

How energy from light is absorbed by an atom

Atom mainly consists of nucleus and orbits (energy levels). Inside the nucleus protons and neutrons are present while electrons reside in the orbits. Each orbit has particular energy. Electron present in particular energy level possess the same energy as of that orbit this is termed as its “ground state”. In order to move to higher orbit electron must have to gain energy equal to the energy of required orbit, after gaining this energy electron is called to be an excited state.

When a photon strikes with an atom it is absorbed by the electron surrounded in orbit this tends that electron to jump to higher energy level, but this all not happen easily, there are some conditions when a photo gets absorbed:

• Photon gets absorbed only when the quantum energy (E=hv) of the photon matches the energy gap between the initial and final transition state (Hyperphysics.phy-astr.gsu.edu, 2017).
• Here, E = energy of light, h =plank’s constant, v= frequency of light

This means that the energy of photon which gets a have to be absorbed by electron must match the energy difference between the energy level in which the electron is present and the energy level to which the electron will move.

How energy from light is absorbed by molecules

When two or more atoms bind together they form a molecule. In the molecular state there are three types of orbitals:

• Anti-bonding (these contain no electron)
• Nonbonding (these contain a lone pair of an electron)
• Bonding (these contain bonding pairs of an electron)

When light passes from a molecule electrons present in nonbonding and bonding orbitals absorb it and jump to anti-bonding orbital. A particular amount of energy is required for each jump. Each wavelength of light have a specific energy. If the wavelength of light possess that enough amount of energy which is required by an electron to jump to a higher level it gets absorbed. (Chemistry LibreTexts, 2017).

How are the orbits and energy states of electrons affected

When the light collides with a molecule which has the same vibrational motion frequency as the light has, the light gets absorbed. This absorbed energy causes the bonds in the molecule to shift in that particular vibrational motion. The vibration occurs in the bonds when the bonds are not rigid (Greiner et al, 2012).Light energy absorption

An electron is evoked from molecular orbital (low-energy to higher energy). This energy states of electrons get affected when there is the difference of energy as ΔE = hν.  The rotational and mechanical vibrational distribution in a matter leads to the collection of molecules in a certain state. This transition of electrons is later accompanied by concurrent changes in rotational and vibrational energy. This eventually results in spectrum absorption. Moreover, high-resolution conditions depict closed spaced lines in a fine structure format. In this way, the energy states of electrons and orbit get affected through energy storage of mechanical vibrations within the molecules.

How the wavelength of the absorbed energy is affected

Light energy absorption Wavelength refers to the distance between two consecutive crust and trough. Wave speed varies in medium, specifically, light speed in the medium is lower than in vacuum. This shows that similar frequency level will link to a short wavelength in the medium rather than in vacuum. The speed of the wave is always determined by its medium, which also imposes different effects includes refraction and diffraction. As per the research of Yu et al (2017), light surpasses from air into water, which certainly brings changes in wavelength. In the solution of a medium, light interacts from different angles and hit the solution. Every single wavelength of the absorbed energy interacts with the molecules presented in the solution.  This absorbed energy gets blocked by molecules or even transmitted. The determining factors of affecting wavelength are medium and speed.

Light energy absorption When the molecules are dissolved in the solvent they interact with the solvent molecules and this tends to change in the wavelength of light, absorbed by the molecules. Solvent molecules can affect the structure wavelength and intensities of the absorption curves. As the polarity of the solvent increase spectra suffers and fine vibrational spectra structure is disturbed this is due to the interaction of solvent with the molecules. Stabilization in the arrangement of solvent molecules which are in the excited state are present more in those molecules which have a strong interaction with a substituent and the nucleus (Homocianu, 2011)….. Read More