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Chemistry / Re: Why do some em wavelengths get absorbed by electrons while others are not?
« on: 01/05/2016 05:23:04 »
The question of transmission (refraction), absorption or, reflection has to do with both the frequency of the EM & where the electrons are in the incident medium.
A conductor like silver has electrons loose & distant from the nucleus; easily moved by an electric field. That's why it reflects light: electric fields can't exist in the silver & sum to zero at its surface (approximately.) The counter electric field produces a direction vector when summed with the magnetic field which results in reflection. Metals generally have this property; to varying degrees.
A block of carbon has electrons held relatively tightly; if it's doped, it can become a semiconductor but, just a block of carbon will pass radio freq. EM fields. Air passes visible light &, that's why the eye & chlorophyl are as they are; in between reflecting & passing is seeing & being colourful. I suppose carbon is black because as the frequency is increased it becomes sufficient to move the electrons up an an orbital before it reaches the visible range; presumably, before the infrared. The electrons jumping orbitals must somehow transmit their energy to the atoms themselves to heat things up; probably some harmonics of electron movement do & some don't.
I don't think the eye would work if the atmosphere with radiation belts (?) wasn't opaque to higher frequency EM radiation.
A conductor like silver has electrons loose & distant from the nucleus; easily moved by an electric field. That's why it reflects light: electric fields can't exist in the silver & sum to zero at its surface (approximately.) The counter electric field produces a direction vector when summed with the magnetic field which results in reflection. Metals generally have this property; to varying degrees.
A block of carbon has electrons held relatively tightly; if it's doped, it can become a semiconductor but, just a block of carbon will pass radio freq. EM fields. Air passes visible light &, that's why the eye & chlorophyl are as they are; in between reflecting & passing is seeing & being colourful. I suppose carbon is black because as the frequency is increased it becomes sufficient to move the electrons up an an orbital before it reaches the visible range; presumably, before the infrared. The electrons jumping orbitals must somehow transmit their energy to the atoms themselves to heat things up; probably some harmonics of electron movement do & some don't.
I don't think the eye would work if the atmosphere with radiation belts (?) wasn't opaque to higher frequency EM radiation.
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