# EMF, radio transmissions and absorption of energy in Oxygen atoms around 60GHz

## Homework Statement:

I am having difficulty understanding what exactly is happening when radio transmissions are being absorbed by oxygen at 60GHz at the atomic level.

## Relevant Equations:

Refraction/reflection, oxygen absorptions/attenuation, frequency
Homework Statement: I am having difficulty understanding what exactly is happening when radio transmissions are being absorbed by oxygen at 60GHz at the atomic level.
Homework Equations: Refraction/reflection, oxygen absorptions/attenuation, frequency

I have tried to find the answers online but I am not sure if I am understanding the material correctly;

Summarizing my understanding (please correct me if I am wrong)

The energy of an electromagnetic field is quantized using the Planck's equation which is dependant on the frequency of the transmission: E=hv. Therefore higher frequencies will have higher energy potential than lower frequencies, In regards to Oxygen, each orbiting electron will have a specific energy level required in order for the electron to move into a higher energy state, therefore at 60GHz this is sufficient energy for the electrons to be absorbed in this case?. Why is the energy absorbed per say?, wouldn't the electrons want to fall into a lower state of energy and emit photons and thus reflected/refracted ? or is there another interaction of collisions with other neighbouring atoms ?

My second query is regarding refractions and reflection, radio waves can be propagated by utilizing the ionosphere, during the day time frequencies up to 30MHz are absorbed by the D layer due ionization and interactions with electrons, the reason why this happens is the wavelength size causes the electrons to displace to such an extent that they collide with neighbouring atoms at thus losing its energy. Higher frequencies can however pass the D layer due to shorter wavelengths. If a wavelength is transmitted at higher frequencies of 30-50MHz they can penetrate the D region and can reflect off the E region. When the wavelength reaches the E region it is reflected due to the excitation and oscillation of electrons causing emission to occur, however the speed at which it travels is slowed due to destructive interreference caused by a phase delay between emission and incoming wavelength which shortens the wavelength and thus reducing its speed: v= f λ, therefore the resulting wavelength is shorter and phase velocity reduced (ie. refraction) ?

Many thanks upfront for any input, I am a student and still trying to make sense of the material, I am studying signalling and communications at the moment.

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Homework Statement: I am having difficulty understanding what exactly is happening when radio transmissions are being absorbed by oxygen at 60GHz at the atomic level.
Homework Equations: Refraction/reflection, oxygen absorptions/attenuation, frequency

Homework Statement: I am having difficulty understanding what exactly is happening when radio transmissions are being absorbed by oxygen at 60GHz at the atomic level.
Homework Equations: Refraction/reflection, oxygen absorptions/attenuation, frequency

I have tried to find the answers online but I am not sure if I am understanding the material correctly;

Summarizing my understanding (please correct me if I am wrong)

The energy of an electromagnetic field is quantized using the Planck's equation which is dependant on the frequency of the transmission: E=hv. Therefore higher frequencies will have higher energy potential than lower frequencies, In regards to Oxygen, each orbiting electron will have a specific energy level required in order for the electron to move into a higher energy state, therefore at 60GHz this is sufficient energy for the electrons to be absorbed in this case?. Why is the energy absorbed per say?, wouldn't the electrons want to fall into a lower state of energy and emit photons and thus reflected/refracted ? or is there another interaction of collisions with other neighbouring atoms ?

My second query is regarding refractions and reflection, radio waves can be propagated by utilizing the ionosphere, during the day time frequencies up to 30MHz are absorbed by the D layer due ionization and interactions with electrons, the reason why this happens is the wavelength size causes the electrons to displace to such an extent that they collide with neighbouring atoms at thus losing its energy. Higher frequencies can however pass the D layer due to shorter wavelengths. If a wavelength is transmitted at higher frequencies of 30-50MHz they can penetrate the D region and can reflect off the E region. When the wavelength reaches the E region it is reflected due to the excitation and oscillation of electrons causing emission to occur, however the speed at which it travels is slowed due to destructive interreference caused by a phase delay between emission and incoming wavelength which shortens the wavelength and thus reducing its speed: v= f λ, therefore the resulting wavelength is shorter and phase velocity reduced (ie. refraction) ?

Many thanks upfront for any input, I am a student and still trying to make sense of the material, I am studying signalling and communications at the moment.
This isn't my area of expertise. But for what it's worth, I think the absorption peak around 60 GHz might have something to do with the interaction between the $\mathrm{O_2}$ molecule's magnetic moment and electromagnetic fields.

J. H. van Vleck wrote a paper about this in 1946, "The Absorption of Microwaves by Oxygen." The paper seems to be referenced fairly often.

[Edit: There's also other papers by J. H. van Vleck and V. F. Weisskopf. From what I can tell, there's a whole theory about this named after them.]

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