What happens when ethane absorbs UV light?

In summary, the conversation discussed the effect of UV light on the bond between carbon atoms in ethane. It was noted that the molecule can disintegrate into different particles due to the excitation of electrons, and this can result in the formation of radicals. The complexity of the topic was also acknowledged and examples of research on the photodissociation of molecules were mentioned. The speaker also clarified that ethane, not ethene, was the molecule of interest.
  • #1
Lotto
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TL;DR Summary
I have a molecule of ethane and when I use UV light, the molecule absorb it, so ethane's electron excitates from HOMO to LUMO. But what happens to the molecule? Does the sigma bond C-C still exist?
Because when I have two carbon atoms, they create a single bond, so their two electrons are in one boding orbital, but I have also one anti-bonding orbital here. And when the electron excitates from ##\sigma## to ##\sigma^*##, how can the bond between the carbon atoms exist? It has to disappear. But what happens next? Does the UV light affect also bonds C-H?
 
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  • #2
Have you conducted a search of the literature? For example on the photodissociation of ethane.
 
  • #3
Hyperfine said:
Have you conducted a search of the literature? For example on the photodissociation of ethane.
I found out that ethene can disintegrate into different particles, so my ideal should be right. And it is caused by the excitation of an electron of the molecule, so it can happen that electron in bonding orbital of C-H excitates into an anti-bonding orbital as well as an electron in C-C bonding orbital excitates.

But in general, when we use UV light, the molecule disintegrates and radicals can arise for instance.
 
  • #4
Lotto said:
But in general, when we use UV light, the molecule disintegrates and radicals can arise for instance.
Indeed, radicals can arise! That fact has been well documented for many decades.

However, you must realize that the topic is very broad and certainly not lacking in complexity. The structure of the initial molecule is very important as is the phase (gas, liquid, solid) in which the process takes place. And then there is the question of the nature of the excited states that are populated. All due care should be taken in considering generalizations.

As but one illustrative example, Ahmed Zewail and his group at Cal Tech pursued detailed investigations of the photodissociation of I2 in rare gas clusters utilizing femtosecond spectroscopic techniques. Who would have guessed that the dynamics would be dependent on the polarizabilty of the rare gas?

You have mentioned both ethane and ethene. Very different molecules with very different energy states. Which one of the two is particular interest to you?
 
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  • #5
Hyperfine said:
Indeed, radicals can arise! That fact has been well documented for many decades.

However, you must realize that the topic is very broad and certainly not lacking in complexity. The structure of the initial molecule is very important as is the phase (gas, liquid, solid) in which the process takes place. And then there is the question of the nature of the excited states that are populated. All due care should be taken in considering generalizations.

As but one illustrative example, Ahmed Zewail and his group at Cal Tech pursued detailed investigations of the photodissociation of I2 in rare gas clusters utilizing femtosecond spectroscopic techniques. Who would have guessed that the dynamics would be dependent on the polarizabilty of the rare gas?

You have mentioned both ethane and ethene. Very different molecules with very different energy states. Which one of the two is particular interest to you?
That ethene was a mistake, I meant ethane.
 

Related to What happens when ethane absorbs UV light?

1. What is ethane and how does it absorb UV light?

Ethane is a hydrocarbon molecule with the chemical formula C2H6. It is a colorless, odorless gas at room temperature. When ethane absorbs UV light, it undergoes a process called photoexcitation, where the UV photons excite the electrons in the molecule to higher energy levels.

2. What happens to ethane molecules after they absorb UV light?

After absorbing UV light, ethane molecules become unstable and undergo chemical reactions. They can either break apart into smaller molecules or form new bonds with other molecules. This process is known as photochemical reaction.

3. How does UV light affect the properties of ethane?

UV light can cause changes in the physical and chemical properties of ethane. It can lead to the formation of new compounds, alter its melting and boiling points, and affect its reactivity with other substances.

4. Is the absorption of UV light by ethane harmful to the environment?

In small amounts, the absorption of UV light by ethane is not harmful to the environment. However, excessive exposure to UV light can lead to the production of harmful pollutants, such as ozone, which can have negative impacts on human health and the environment.

5. Can ethane be used as a UV blocker?

Ethane itself does not have the ability to block UV light. However, it can be used as a building block for creating UV-blocking compounds, such as sunscreen ingredients. These compounds absorb or reflect UV light, protecting the skin from its harmful effects.

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