Spectrum of absorption of light and emission of heat/IR

[OxygenBlue]

Hi everybody

 

When a material absorps a certain kind of electromagnetic radiation - let's say blue light - the energy in the light has to go somewhere. My guess is that it would heat up the material by making it vibrate. How ever it came to my mind that it could work like fluorescence, where a wavelength is absorbed and a lower wavelength is emitted. So my question is, does a coloured material have a emission spectrum in the IR-range corresponding to its absorbtions spectrum when it is illuminated by continious white light?

 

Another question in the same topic. Wikipedia states, that the energy difference between absorbed and emittet light in a flourescenct matterial is nonradioactive decay i.e. heat... but wouldent a heating up of the material make it radiate?

 

Thanks for any input!

[swansont]

Hi everybody

 

When a material absorps a certain kind of electromagnetic radiation - let's say blue light - the energy in the light has to go somewhere. My guess is that it would heat up the material by making it vibrate. How ever it came to my mind that it could work like fluorescence, where a wavelength is absorbed and a lower wavelength is emitted. So my question is, does a coloured material have a emission spectrum in the IR-range corresponding to its absorbtions spectrum when it is illuminated by continious white light?

 

I'm not sure what you mean by the last sentence — by white light do you mean visible-only spectrum?

 

Depending on the material, you can have lots of IR transitions, often vibrational or rotational modes of molecules. However the blackbody spectrum of a material is continuous.

 

Another question in the same topic. Wikipedia states, that the energy difference between absorbed and emittet light in a flourescenct matterial is nonradioactive decay i.e. heat... but wouldent a heating up of the material make it radiate?

 

Thanks for any input!

 

Yes, an object radiates according to its temperature. This is not due to nuclear transitions or interactions, so it's not because the material is radioactive.

[OxygenBlue]

I'm not sure what you mean by the last sentence — by white light do you mean visible-only spectrum?

 

Depending on the material, you can have lots of IR transitions, often vibrational or rotational modes of molecules. However the blackbody spectrum of a material is continuous.

 

But is ther flourescent materials, that emit (a certain spectrum) in the IR-range?

[swansont]

But is ther flourescent materials, that emit (a certain spectrum) in the IR-range?

 

There tend to be a lot of IR transitions, so one might have a hard time seeing a spectrum, but yes, there are, and probably a lot of materials that do this.