| Topic: |
Science > Physics |
| User: |
"Landle" |
| Date: |
11 Jan 2005 04:15:02 PM |
| Object: |
Energy Levels Hopping |
When an electron jumps from a higher state to a lower state
(let's say ground state), how come the light produced
is only one frequency (such as red) giving the nature of
line spectrum. What should the arrangements of the electrons
be to give continuous white light spectrum (at all frequency
ranges)? Could there be other atomic model without energy
levels hopping that can cause atomic line spectrum too?
Has any instrument actually *seen* these energy levels
and states or is it all just a theoretical model without
solid direct proof?
Landle
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| User: "Franz Heymann" |
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| Title: Re: Energy Levels Hopping |
12 Jan 2005 02:02:17 AM |
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"Landle" <landlematt@yahoo.com> wrote in message
news:1105481702.163287.16330@f14g2000cwb.googlegroups.com...
When an electron jumps from a higher state to a lower state
(let's say ground state), how come the light produced
is only one frequency (such as red) giving the nature of
line spectrum. What should the arrangements of the electrons
be to give continuous white light spectrum (at all frequency
ranges)? Could there be other atomic model without energy
levels hopping that can cause atomic line spectrum too?
Has nobody told you that atomic spectra contain a continuum as well as
sharp lines?
Has any instrument actually *seen* these energy levels
and states or is it all just a theoretical model without
solid direct proof?
Yes and no in that order.
Franz
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| User: "Uncle Al" |
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| Title: Re: Energy Levels Hopping |
11 Jan 2005 06:37:40 PM |
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Landle wrote:
When an electron jumps from a higher state to a lower state
(let's say ground state), how come the light produced
is only one frequency (such as red) giving the nature of
line spectrum.
It isn't a monochromatic delta function. There are vibration and
rotation sublevels (polyatomics) possibly mixed, spin interactions
(especially messy with heavy atoms), and hyperfine levels for nuclear
spin interactions. Doppler shift, too, plus natural line width,
stimulated decay, and Heisenberg. The number of truly intrinsically
narrow spectral lines is very small - used in atomic clocks.
What should the arrangements of the electrons
be to give continuous white light spectrum (at all frequency
ranges)?
Blackbody; thermal continuum source (incandescent light).
Pressure-broadened multi-line source (Lucalux). Doped emission (rare
earth iodides in Hg-Ar short arc lamps). I doubt you have ever seen
true white light. Retinas are clever.
Could there be other atomic model without energy
levels hopping that can cause atomic line spectrum too?
No, or untenured faculty would publish.
Has any instrument actually *seen* these energy levels
and states or is it all just a theoretical model without
solid direct proof?
William Hyde Wollaston, 1802
Joseph von Fraunhaufer, 1813.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "Franz Heymann" |
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| Title: Re: Energy Levels Hopping |
12 Jan 2005 02:02:17 AM |
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"Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:41E47153.CAE5A7F6@hate.spam.net...
Landle wrote:
When an electron jumps from a higher state to a lower state
(let's say ground state), how come the light produced
is only one frequency (such as red) giving the nature of
line spectrum.
It isn't a monochromatic delta function. There are vibration and
rotation sublevels (polyatomics) possibly mixed, spin interactions
(especially messy with heavy atoms), and hyperfine levels for
nuclear
spin interactions. Doppler shift, too, plus natural line width,
stimulated decay, and Heisenberg.
You forgot an important player:
Free-Free and Free-Bound transitions, both of which yield continuous
spectra.
Franz
The number of truly intrinsically
narrow spectral lines is very small - used in atomic clocks.
What should the arrangements of the electrons
be to give continuous white light spectrum (at all frequency
ranges)?
Blackbody; thermal continuum source (incandescent light).
Pressure-broadened multi-line source (Lucalux). Doped emission
(rare
earth iodides in Hg-Ar short arc lamps). I doubt you have ever seen
true white light. Retinas are clever.
Could there be other atomic model without energy
levels hopping that can cause atomic line spectrum too?
No, or untenured faculty would publish.
Has any instrument actually *seen* these energy levels
and states or is it all just a theoretical model without
solid direct proof?
William Hyde Wollaston, 1802
Joseph von Fraunhaufer, 1813.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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| User: "Bjoern Feuerbacher" |
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| Title: Re: Energy Levels Hopping |
12 Jan 2005 03:21:45 AM |
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Landle wrote:
When an electron jumps from a higher state to a lower state
(let's say ground state), how come the light produced
is only one frequency (such as red) giving the nature of
line spectrum.
It is not only one frequency. It is in fact a broadened
line. Look up "natural line width".
That it is at least *approximately* a single line is due
to the simple fact that the transition is between two states
with definite energy.
What should the arrangements of the electrons
be to give continuous white light spectrum (at all frequency
ranges)?
Try bremsstrahlung. But even that will have a cut-off frequency.
Could there be other atomic model without energy
levels hopping that can cause atomic line spectrum too?
If there are lines, it follows logically that the transitions
have to be between fixed, definite energy levels.
Has any instrument actually *seen* these energy levels
and states or is it all just a theoretical model without
solid direct proof?
Experimental physics isn't about proof.
But yes, there is indeed *evidence* that the orbitals do
indeed exist. Coming from scattering (determining the local
charge density) and from atomic force microscopy.
Bye,
Bjoern
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| User: "Mark Martin" |
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| Title: Re: Energy Levels Hopping |
11 Jan 2005 04:57:44 PM |
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Landle wrote:
When an electron jumps from a higher state to a lower state
(let's say ground state), how come the light produced
is only one frequency (such as red) giving the nature of
line spectrum. What should the arrangements of the electrons
be to give continuous white light spectrum (at all frequency
ranges)? Could there be other atomic model without energy
levels hopping that can cause atomic line spectrum too?
Has any instrument actually *seen* these energy levels
and states or is it all just a theoretical model without
solid direct proof?
The light emitted due to an electron changing orbitals is necesarily of
one frequency, the one corresponding to the energy difference in the
two orbitals. Continuous spectra aren't due to to electronic jumps.
They are created by whole populations of atoms vibrating due to their
temperature.
If you heat a body of atoms, for instance a chunk of Iron, the heat
energy goes into vibrating the atoms about their individual equilibrium
positions. As an atom vibrates in this way it's accelerated, and its
electric field aquires a wave with frequency equal to the vibration.
These waves are light that you can see if its bright enough, and within
the eye's range of visible frequencies. But not all the myriad atoms
end up vibrating at the same rate. There's a statistical distribution
of frequencies over the whole mass of oscillators, so the large, hot
chunk of Iron emits a broad spectrum of colors.
And yes, the process you refer to is a theory. No one can look down and
graphically see the electronic orbitals. What we have is the spectral
data itself, from which the highly successful theory is abstracted.
It's not impossible that another model or theory can recreate the line
spectra of atoms. Bohr's model did so perfectly for Hydrogen. But a
model is just a construct that reproduces the exact data which it
addresses. A theory goes beyond that and asserts to predict the data
from experiments not yet done, in domains not yet tapped. The test then
is to actually do experiments in those domains. This is where quantum
mechanics comes in. Quantum mechanics was a culmination of many years'
progress in understanding atomic physics, and with it the Bohr model
became just a souvenir.
Quantum mechanics is *severely* successful in a large domain outside
that which inspired it. In order for another theiry to be better, it'd
have to do everything QM does, and then some. So far this just hasn't
happened.
-Mark Martin
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