Will CO2 absorb photon in all directions?

[RealityCheck]

First attempt: to see how much addition velocity a molecule of CO2 would have after absorbing IR photon.

frequency 2349, Plank's constant 6.63E-34 Energy 1.56E-30 J mass .31E-26 kg Velocity 0.00652568 Meters/sec.
frequency 667, Plank's constant 6.63E-34 Energy 4.42E-31 J mass 7.31E-26 kg Velocity 0.00347734 Meters/sec.


So that seems a surprisingly small rate increase considering molecules are moving at 100s of meters per second in room temperature air.
and after a IR ray is absorbed by it it only rises by as little as 7/1000 ths of a meter/sec?

Hi Robbitybob1.

You need to consider also the fact that CO2 molecules are constantly accelerating/decelerating during/after collisions which are occurring at fantastically high rates with other CO2 and Oxygen, Nitrogen etc molecules and dust/water vapor.

During these varying changes in accelerations/attitudes the CO2 and other (methane) molecules provide a wide 'cross-section' of 'approach/recession' states for absorbtion of IR radiation over a spectrum made possible by the doppler shift' MATCHING during such collision approach/exiting decelerating/accelerating?

Cheers and g'night, Rb1, everyone!

.

 

[Robittybob1]

Yes this increased velocity over the average velocity of the gas as a whole is transferred during the elastic collisions with the other molecules. Because the CO2 has been accelerated the energy gained can be passed onto the other surrounding gas particles. The vibration stops and the molecule is ready to absorb another IR photon.

 

[Robittybob1]

Now the purpose of the thread was to see if we can prove whether it is possible for the GHG to absorb the IR irrespective of what direction it was going (by that I mean it would have the right alignment for absorption but the difference being that the IR photon is going in the opposite direction to the motion of the molecule.

So what we will need to do is to understand what conservation of momentum and energy means in the case of photon absorption.

One thing as far as electron absorptions go it generally is an all or none response. By that I mean is that the electron takes the whole of the energy and momentum contained in the photon and not just a portion of it.

So that seems to be an interesting situation where the same reaction can deal with momentum and energy in the same interaction.
So the next few posts will need to be about conservation of momentum and energy.

 

[Robittybob1]

.....One thing as far as electron absorptions go it generally is an all or none response. By that I mean is that the electron takes the whole of the energy and momentum contained in the photon and not just a portion of it.....

With Compton Effect, high energy photons are directed toward solid material and they will knock out electrons with a certain amount of momentum. There will often be a residual photon deflected in another direction that takes the balance of the momentum and energy.
So there seems to be 3 types of photon electron interaction. Compton Effect, Photoelectric effect where the electron rises up the electron levels absorbing the full energy momoentum of the photon, and this low energy IR interation where the photon sets up vibrations in the electron and molecular bonds.
This is the state of my understanding at this stage. But I wanted to make it clear it is not always an all or nothing interaction.

 

[Robittybob1]

Here's something I didn't know

The energy of a photon is linearly proportional to its momentum. When plotted
on the same graph as that for an electron, the energy–momentum relationship for a photon looks like a vertical line.
from spie.org/samples/PM167.pdf

So a free electron never interacts wth a photon.

 

[Robittybob1]

Energy of photon = Planck's Constant * frequency

Momentum of Photon = (Planck's Constant * frequency)/speed of light

So when you look at the equation the numerical value of the momentum is going to be proportional but also 3*10^8 smaller.
When compared to physical masses at mundane velocities energy and momentum can have similar values. e.g. a 1 kg mass travelling at 2 m/sec the Kinetic energy and momentum both equal 2.

So it is safe to say, and the work I've done comparing the two momentum situations further emphasised this, that photons have momentum but only a small amount.

 

[Robittybob1]

For the two frequencies that CO2 absorbs.
frequency - 2349 Hz, c = speed of light =3.00E+08, Planck's constant = 6.63E-34, Photon energy =1.56E-30 Joules Photon momentum 5.19E-40, Resultant velocity = 7.10E-14 m/sec.

frequency - 667 Hz, c = speed of light = 3.00E+08, Planck's constant = 6.63E-34, Photon energy = 4.42E-31 Joules, Photon momentum 1.47E-40, Resultant velocity = 2.02E-14 m/sec.

So does that mean after the photon has attacted itself to the Carbon dioxide there will be an increase in velocity in the direction of the momentum of either 7.10 or 2.02 x 10^ -14 meters/sec.
So that was my point from the beginning - how can the momentum be conserved if the Carbon dioxide molecule is already traveling against the momentum of the photon?

 

[Robittybob1]

So that was my point from the beginning - how can the momentum be conserved if the Carbon dioxide molecule is already travelling against the momentum of the photon?

So you get the situation where unless the photon can conserve its momentum it won't interact with the electrons on the Carbon Dioxide molecule. It can clearly be seen that the electron has to be either stationary or at least have momentum in the direction of the photon's momentum vector before conservation of momentum can occur.
That then leads to the conclusion that GHG when they heat up the atmosphere also provide an impetus to super-rotate the planet for there is more heating occurring on the side going away from the source of the photons (the Sun) than on the side approaching the source.
So the planets covered with GHG will experience an intensified wind in the direction of rotation. This intensified wind will exert a drag effect on the planet's surface and over the lifetime of the planet contribute to the angular velocity of spin and hence shorten the planet's "day length".

 

[OnlyMe]

So you get the situation where unless the photon can conserve its momentum it won't interact with the electrons on the Carbon Dioxide molecule. It can clearly be seen that the electron has to be either stationary or at least have momentum in the direction of the photon's momentum vector before conservation of momentum can occur.
That then leads to the conclusion that GHG when they heat up the atmosphere also provide an impetus to super-rotate the planet for there is more heating occurring on the side going away from the source of the photons (the Sun) than on the side approaching the source.
So the planets covered with GHG will experience an intensified wind in the direction of rotation. This intensified wind will exert a drag effect on the planet's surface and over the lifetime of the planet contribute to the angular velocity of spin and hence shorten the planet's "day length".

I don't think the implications for weather can be so easily codified. Venus, has a GHG problem and both high temperatures and high winds, but I am unsure they are entirely consistent your above conclusions.

That bit aside over time the length of an earth day has grown. I seem to recall some mention that a few years back, as in long long ago, a day was as short as six hours and the moon was near close enough to touch. Of corse I exagerate about touching the moon, I don't believe fingers had yet evolved at the time. (a little humor)

Really think about the mass and momentum of the earth compared to the atmosphere... Any affect of atmospheric winds on the rotation of the earth must happen over a time scale that would make them insignificant when compared to many other forces in play.

But there is another aspect of likely more significance, the motion of GHG molecules in the atmosphere are generally random and average out. So the real significance is that while the sun shines they allow heat in and when it does not that act as an insulator to prevent its escape.

 

[Billy T]

To Robittbob1

The energy and the momentum of a photon are both linearly proportional to its frequency, so of course they are linearly proportional to each other. Also the photon can Compton scatter off a free electon - In fact Compton X-rays have so much energy that even a bound electon is "free" to them. A plasma will scatter light, not very much as very low density, but not so low when normalize by "electons per cc").

Due to scattering´s "random walk" nature and other things, photon at the solar core, take many months (YEARS, I SEEM TO RECALL) to excape to solar surface and then gets to earth in only 8.5 minutes, but it is a little strange to say this as the photon energy changes drastically during the process reaching the surface to a much lower value.

For "earth shine" IR ratiation the CO2 might absorb there are no elections removed from the CO2. Also the IR rotational and vibrational absorption band are not due to movement of an electron alone. It is the whole molecule, which is linear of the form: o--c--o. I can not draw for you it rotating but there are two distinct form of pure vibration:

(1)Symetric stretch: o-c-o going to o---c---o and back again

(2) A-symetric stretch: o-c--o going to o--c-o and back again.

In addition there are the flex modes (which are harder to type draw):
o.......o
....c.... (ignore all dots - they are just to keep Sciforum´s compter from compressing multiple spaces down to one.)
Going to:
....c....
o.......o

 

[Robittybob1]

I don't think the implications for weather can be so easily codified. Venus, has a GHG problem and both high temperatures and high winds, but I am unsure they are entirely consistent your above conclusions.

That bit aside over time the length of an earth day has grown. I seem to recall some mention that a few years back, as in long long ago, a day was as short as six hours and the moon was near close enough to touch. Of corse I exagerate about touching the moon, I don't believe fingers had yet evolved at the time. (a little humor)

Really think about the mass and momentum of the earth compared to the atmosphere... Any affect of atmospheric winds on the rotation of the earth must happen over a time scale that would make them insignificant when compared to many other forces in play.

But there is another aspect of likely more significance, the motion of GHG molecules in the atmosphere are generally random and average out. So the real significance is that while the sun shines they allow heat in and when it does not that act as an insulator to prevent its escape.

Well this only applies to the current Earth situation in a very minor way as the GHG are only a small fraction of the Earth's atmosphere.
Add to that the effect of tidal angular momentum transfer to the Moon which is slowing the Earth. So there are opposing effects and they are beyond sorting them out.

But as you point out prior to the Moon (being a slowing influence) the Earth was roaring around at a frightening rate, and fully covered with a range of GHG at that time.

Venus definitely doesn't have a Moon now but was thought to have had one. The collision of it's moon may have stopped it spinning the way all other (bar 1) planets do (counter clockwise) so I think of Venus' atmosphere speeding up its rotation in the way it is now going.

Jupiter is the prime example of this effect on the planets spin. No scientist can offer the reason it spins as fast yet I believe the effect I have described accounts for some of it.

The other planets I'm just not sure about at this stage of my study.

Also the random nature of the heating only appears on the Earth where the atmosphere is clear enough for the sunlight to strike the land surface. On planets orbiting the Sun, even if they were not rotating with respect to the stars, as they orbited the Sun, from the Sun's perspective the planet will rotate once per year. Hence as far as the incoming radiation from the Sun is concerned the photons absorbed by GHG will tend to occur on the side appearing to be going away from the Sun, not the approaching side.
Now I do realise that due to the angular momentum in the planetary dust disc, from the beginning, it is unlikely that the forming planets did not have some spin from the very beginning.

 

[Robittybob1]

To Robittbob1

The energy and the momentum of a photon are both linearly proportional to its frequency, so of course they are linearly proportional to each other. Also the photon can Compton scatter off a free electon - In fact Compton X-rays have so much energy that even a bound electon is "free" A plasma will scatter light. Due to scattering and other things, photon at the solar core, take many months (YEARS, I SEEM TO RECALL) to excape and then get to earth in only 8.5 minutes, but it is a little strange to say this as the photon energy changes drastically during the process to a much lower value.

For "earth shine" IR ratiation the CO2 might absorb there are no elections removed from the CO2. Also the IR rotational and vibrational absorption band are not due to movement of an electron alone. It is the whole molecule, which is linear of the form: o--c--o. I can not draw for you it rotating but there are two distinct form of pure vibration:

(1)Symetric stretch: o-c-o going to o---c---o and back again

(2) A-symetric stretcjh: o-c--o going to o--c-o and back again.

In addition there are the flex modes (which are harder to type draw):
o.......o
....c.... (ignore all dots - they are just to keep Sciforum´s compter from compressing multiple spaces down to one.)
Going to:
....c....
o.......o

I think I agree with what you have said. The IR appears to always interact with an electron, but it doesn't cause ionization in the case of IR radiation. The electron is not ripped off. But it is advanced and that advancement causes the molecule to vibrate. That vibration (like plucking the string on a guitar was started by a distinct motion, stretching the molecular bonds (but not breaking them). That distinct motion is in the direction of the momentum vector so with time the molecule as a whole moves in the same direction as the "strum".

Continuing the analogy of the guitar. If the guitar was on a frictionless surface and it was continually strummed "downward" across the strings it would overcome inertia and move in the same direction as the strum.

 

[Robittybob1]

To Robittbob1 ....
Also the photon can Compton scatter off a free electon - In fact Compton X-rays have so much energy that even a bound electon is "free" A plasma will scatter light......

Just to look at this piece. Look it has been a while since looking at the Compton effect and it could be so dramatic in ripping electrons of here there and everywhere that the momentum is not such that it will cause any rotation. I have heard in the upper atmosphere regions there are ionised particles that may have gone through the stages you mention. Whether this results in high level winds I am unsure. But the GHG are very effective in converting heat into motion and it in the end creates winds that super-rotate the planets.
I must now tabulate each planet and see if it has been affected this way or not.
For a starter Mercury has virtually no atmosphere and is not spinning rapidly.
Venus has been discussed, high winds and loads of GHGs.
Earth very little atmosphere, patchy winds but possibility of winds building in intensity with global warming.
Jupiter - classic super-rotating winds spinning up the planet to breakneck speeds.
Mars, Neptune and Saturn I'm unsure about.
But on Uranus there are also super-rotating winds

Pluto ??

 

[Robittybob1]

Must see if this can be properly written up. I think it is significant!

 

[Billy T]

I think I agree with what you have said. The IR appears to always interact with an electron, but it doesn't cause ionization in the case of IR radiation. The electron is not ripped off. But it is advanced and that advancement causes the molecule to vibrate. That vibration (like plucking the string on a guitar was started by a distinct motion, stretching the molecular bonds (but not breaking them). That distinct motion is in the direction of the momentum vector so with time the molecule as a whole moves in the same direction as the "strum". ....

Your idea that the IR´s electric field pulls on just one electron of the molecule is False.
The IR interaction is with the entire molecule. Don´t guess and post – learn the facts instead of misleading others.

The shortest wavelength called IR is 1 micron long and the longest is 1000 microns. The typical size of molecule (of a few atoms) is 0.001 micron. (DNA, etc. and polimers etc. are much larger.) Thus one wavelength of even the shortest IR spans something like 1000 moleclues. And one wavelength of the longest IR extends over a million molecules side by side!

References:
Visible light refers to wavelengths between 3000 and 10000 Angstroms. Moving down in energy, Infrared light refers to wavelengths between 10000 Angstroms(= 1 micron) and 1000 microns (- 1 millimeter). From: http://books.google.com.br/books?id...e&q=Infrared wavelengths in angstroms&f=false

The size of a molecule is typically of the order of a millimicron (10~7 cm) or less (Angstrom, 10~8 cm). The size of an atom equals a few Angstroms.

From: http://books.google.com.br/books?id...page&q=size of molecules in angstroms&f=false
Which is book you can read on line, if you want to learn molecular / radiation Physics. Don´t just make things up and post your beliefs.

Must see if this can be properly written up. I think it is significant!

No - mainly False, unfounded beliefs of one guy.

 

[OnlyMe]

Your idea that the IR´s electric field pulls on just one electron of the molecule is False.
The IR interaction is with the entire molecule. Don´t guess and post – learn the facts instead of misleading others.

The shortest wavelength called IR is 1 micron long and the longest is 1000 microns. The typical molecule of a few atoms is of size is 0.001 micron. Thus one wavelength of even the shortest IR spans something like 1000 moleclues. And one wavelength of the longest IR extends over a million molecules side by side!

References:
Visible light refers to wavelengths between 3000 and 10000 Angstroms. Moving down in energy, Infrared light refers to wavelengths between 10000 Angstroms(= 1 micron) and 1000 microns (- 1 millimeter). From: http://books.google.com.br/books?id...e&q=Infrared wavelengths in angstroms&f=false
The size of a molecule is typically of the order of a millimicron (10~7 cm) or less (Angstrom, 10~8 cm). The size of an atom equals a few Angstroms. From: http://books.google.com.br/books?id...page&q=size of molecules in angstroms&f=false
Which is book you can read on line, if you want to learn molecular / radiation Phyics. Don´t just make up and post your beliefs. Visible light refers to wavelengths between 3000 and 10000 Angstroms. Moving down in energy, Infrared light refers to wavelengths between 10000 Angstroms(= 1 micron) and 1000 microns (- 1 millimeter).

I am a bit confused here. It seems to me that lasers are used to cool helium to near 0 kelvin, while even blue or violet light is on the order of 430 microns. This is far greater than the size of an atom and yet light even in the visible spectrum seems to interact with single atoms as well as molecules, even potentially with individual particles...

I don't understand the connection between wavelength and the size of an atom or molecule, when potential interaction is the issue. I had always understood or misunderstood the potential interaction to be relative to an atom's, molecule's or even particle's interaction with the specific energy level of the photon.

 

[Robittybob1]

Your idea that the IR´s electric field pulls on just one electron of the molecule is False.
The IR interaction is with the entire molecule. Don´t guess and post – learn the facts instead of misleading others.

The shortest wavelength called IR is 1 micron long and the longest is 1000 microns. The typical size of molecule (of a few atoms) is 0.001 micron. (DNA, etc. and polimers etc. are much larger.) Thus one wavelength of even the shortest IR spans something like 1000 moleclues. And one wavelength of the longest IR extends over a million molecules side by side!

References:
Visible light refers to wavelengths between 3000 and 10000 Angstroms. Moving down in energy, Infrared light refers to wavelengths between 10000 Angstroms(= 1 micron) and 1000 microns (- 1 millimeter). From: http://books.google.com.br/books?id...e&q=Infrared wavelengths in angstroms&f=false

The size of a molecule is typically of the order of a millimicron (10~7 cm) or less (Angstrom, 10~8 cm). The size of an atom equals a few Angstroms.

From: http://books.google.com.br/books?id...page&q=size of molecules in angstroms&f=false
Which is book you can read on line, if you want to learn molecular / radiation Physics. Don´t just make things up and post your beliefs.
No - mainly False, unfounded beliefs of one guy.

@ BillyT I have been reading up on this for some time now, and so I am a bit horrified that you come in so strong saying I am wrong without directing me to scientific papers that support your proposition.

If you read what I say, the interaction is across the whole molecule, but from all my reading so far, a photon usually reacts with the electrons in the first instance. The electron is part of the whole molecule when it is not ripped off in an ionization interaction.
Where is there photon - proton interactions described or photon - neutron interactions described?

The shortest wavelength called IR is 1 micron long and the longest is 1000 microns. The typical size of molecule (of a few atoms) is 0.001 micron. (DNA, etc. and polymers etc. are much larger.) Thus one wavelength of even the shortest IR spans something like 1000 molecules. And one wavelength of the longest IR extends over a million molecules side by side!

This is interesting but what does it prove?

I have calculated the momentun transfer to the whole molecule of CO2. I have argued the case from a conservation of momentum case. I don't see you trying to disprove my results or even using these words in your reply.

I feel your response is a bit unfair considering your title as "moderator".

 

[Billy T]

... what I say, the interaction is across the whole molecule, but from all my reading so far, a photon usually reacts with the electrons in the first instance. The electron is part of the whole molecule when it is not ripped off in an ionization interaction.
Where is there photon - proton interactions described or photon - neutron interactions described? This is interesting but what does it prove ...

As the wave length is so long compared to the size of the CO2 molecule all parts of it are in essentailly the same electric field of the IR radiation at any instant.

The protons and electrons, both have one unit of charge so have essentially the same force magnitude acting on them, at every instant in time, but the force is oppositely directed. The proton is about 1900 times heavier so it accelerates less by that mass ratio. If you like You can classically (and somewhat incorrectly) think of all the electons being pulled first one way then the other wrt the protons. However, still speaking classically,* the total field on the electrons is not the same, as the inter shell electrons "feel" the stonger nuclear attraction field.

It was mainly the following "acts on one electron" nonsense I was trying to correct by telling the relative size of the IR wave length and the CO2 molecule:

... The IR appears to always interact with an electron, but it doesn't cause ionization in the case of IR radiation. The electron is not ripped off. But it is advanced and that advancement causes the molecule to vibrate. ....

The subject you are just now coming to is at least 100 years old - learn some molecular radiation physic that was known generations ago.

* this is inherently a quantum physic problem and there are things in it with no classical analogues. The exclusion principle and the "exchange energy" due to all electrons being identical to name two.

BTW, I DID give you references - one a book you can read to learn what you are posting ideas about.

 

[Robittybob1]

As the wave length is so long compared to the size of the CO2 molecule all parts of it are in essentailly the same electric field of the IR radiation at any instant.

The protons and electrons, both have one unit of charge so have essentially the same force magnitude acting on them, at every instant in time, but the force is oppositely directed. The proton is about 1900 times heavier so it accelerates less by that mass ratio. If you like You can classically (and somewhat incorrectly) think of all the electons being pulled first one way then the other wrt the protons. However, still speaking classically, the total field on the electrons is not the same, as the inter shell electrons "feel" the stonger nuclear atraction field.

It was mainly the following "acts on one electron" nonsense I was trying to correct by telling the relative size of the IR wave length and the CO2 molecule:The subject you are just now coming to is at least 100 years old - learn some molecular radiation physic that was known generations ago.

I am going to read a bit more over the next few days to get the concept right. But from my old science days a photon comes along with the right frequency and raises the electron to another energy level. OK I am a veterinarian not a physicist so the jargon may not be perfect.
But in all the time I have read about electrons moving between energy levels and giving off photons to return to lower energy levels, you are the first to mention that the protons are also affected and that the photon maybe influencing all the electrons on that atom and possibly atoms beside it. You might be right, but that has never been discussed much.

 

[Billy T]

I am a bit confused here. It seems to me that lasers are used to cool helium to near 0 kelvin, while even blue or violet light is on the order of 430 microns. This is far greater than the size of an atom and yet light even in the visible spectrum seems to interact with single atoms as well as molecules, even potentially with individual particles...
I don't understand the connection between wavelength and the size of an atom or molecule, when potential interaction is the issue. I had always understood or misunderstood the potential interaction to be relative to an atom's, molecule's or even particle's interaction with the specific energy level of the photon.

Yes, The way the LASER cools is based on the very sharp line resonance of dilute gas and of the Laser radiation. I.e. Any atom moving will have a Doppler effect that can make some atoms be a perfect frequency match to the laser, but others with different motions will not absorb the laser radiation. I forget all the details but basically you pump out of the trap region all but those atoms with one motion but Temperature is their RANDOM motion component, which is nearly zero if all are moving in same direction with same speed.

Unlike scattering, absorption of a photon is binary – it removes all the photon or none. There is not any really good way to understand classically how the huge by comparison photon is “eaten” by the tiny atom. The closest classical interaction is seen in devices that take energy from water waves. They too are very small compared to the open ocean wave lengths. Also a tiny antenna can radiate wave lengths 100 times larger than it is. As you get to long IR wave lengths there is very little value in speaking in terms of photons, and none for microwaves or longer.