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July 31, 2025, 04:01:18 am
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Andiio

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IR Spec question
« on: April 27, 2011, 06:34:05 pm »
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Hey guys!

Why don't diatomic molecules such as O2 and N2 absorb infrared radiation?

Do we have to know this for the Unit 3 exam or is it beyond the course?

Thanks!
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kushwoho44

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Re: IR Spec question
« Reply #1 on: April 27, 2011, 06:36:52 pm »
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No dipole moment. As the electrons are equally attracted to each atom...

That's all I know, NO idea how that influences IR
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scocliffe09

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Re: IR Spec question
« Reply #2 on: April 27, 2011, 06:53:40 pm »
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Quote from: Andiio on April 27, 2011, 06:34:05 pm
Hey guys!

Why don't diatomic molecules such as O2 and N2 absorb infrared radiation?

Do we have to know this for the Unit 3 exam or is it beyond the course?

Thanks!
Diatomic homonuclear (two of the same atom) molecules don't absorb IR because they don't have a dipole moment and therefore their dipole moment has no net change when they vibrate.
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Mao

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Re: IR Spec question
« Reply #3 on: April 27, 2011, 08:06:59 pm »
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Quote from: scocliffe09 on April 27, 2011, 06:53:40 pm
Quote from: Andiio on April 27, 2011, 06:34:05 pm
Hey guys!

Why don't diatomic molecules such as O2 and N2 absorb infrared radiation?

Do we have to know this for the Unit 3 exam or is it beyond the course?

Thanks!
Diatomic homonuclear (two of the same atom) molecules don't absorb IR because they don't have a dipole moment and therefore their dipole moment has no net change when they vibrate.

^^This.

But this is wayyyy wayyyyyyyyy above VCE level.
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