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I do not agree with the "word" "wavenumber". I think that it ought to be "wave-number" all the way through. The English language does not create new compound words willy-nilly. It is not German.
I've seen the quantitiy "circular wavenumber" referred to as "angular wavenumber". "Angular" seems to be a bit more descriptive and follows the pattern of "angular frequency". (No one says "circular frequency", but language is not always symmetrical or sensible.) Also, Google finds more pages with "angular wavenumber" than "circular wavenumber". Should we retitle the "circular wavenumber" section and mention both quantity names? Zeroparallax 10:54, 17 March 2006 (UTC)
The solutions to a physics HW we had involved what it called the "wavenumber" "k", and it said that:
Does this correspond with anything? I can't find anything about that formula anywhere, and our physics teacher didn't actually teach it to us, although I guess he thinks he did. That and I can't get it to reconcile with de Broiglie's relations. Anyone have any idea what he's talking about? Fresheneesz 06:49, 8 May 2006 (UTC)
In summary, the correct relationship is:
This relationship defines the angular wavenumber of a matter wave (for example an electron) in terms of its mass, its kinetic energy, and Planck's constant (divided by 2 pi). Another correct relationship is:
This relationship defines the angular wavenumber of a matter wave in terms of its momentum and Planck's constant (divided by 2 pi). These relationships hold true for a particle in a box ( quantized angular wavenumbers) or free particle ( continuous angular wavenumbers) because they simply restate the de Broiglie's relations. In fact the page on de Broiglie's relations refers to this article on wavenumber. Therefore the wavenumber article should refer to de Broiglie's relations. The field is quantum mechanics. -- John David Wright 22:29, 23 February 2007 (UTC)
This page need to specify the conversion factors between wavenumbers (cm-1) and Energy/angular frequency, preferably in terms of fundamental constants if that is possible. —Preceding unsigned comment added by 82.35.34.20 ( talk • contribs)
It would be easier to understand the concept if we use plain language appropriate to an encyclopedia. I suggest replacing:
Wavenumber in most physical sciences is a wave property inversely related to wavelength, having SI units of reciprocal meters (m−1).
With:
Wavenumber in most physical sciences is a wave property inversely related to wavelength, having SI units of cycles per unit length or radians per unit length, where the unit length is stated and is typically meters, centimeters, nanometers etc. The dimensions are L-1.
Also:
"The energy corresponds to a wavenumber of 300 reciprocal centimeters (or inverse centimeters or per centimeter)"
would be more clearly: "The energy corresponds to a wavenumber of 300 cycles per centimeter"
Any comments?
GilesW (
talk)
07:30, 22 April 2009 (UTC)
In the context of RF coils etc., please define "radial wavenumber". It is said to be "all important" [ [1]], (see second page between expressions (3) and (4)). I cannot find a definition. GilesW ( talk) 07:56, 8 May 2009 (UTC)
In this edit, physicist User:Dicklyon threw the whole article around, calling spectroscopy an oddball field. But to hosts of chemists and biologists, wavenumbers has no other meaning than a unit of energy. The lead of this article now ignores that. It only explains this term as angular wavenumber, which is the magnitude of the wave vector, of relevance only to physicists that should already know what this is anyway. The article should aim at the general reader, which is someone who wants to know what it means that a " Raman peak is at 300 wavenumbers". / Pieter Kuiper ( talk) 07:41, 24 March 2010 (UTC)
This edit:
http://en.wikipedia.org/?title=Wavenumber&diff=prev&oldid=33599618
seems inconsistent with . The equation, as it presently appears, is:
but should (I think) be:
Comments? —Preceding unsigned comment added by 70.234.243.222 ( talk) 02:14, 11 April 2010 (UTC)
I was curious as to what the connection is between wave number and curvature. Why would you have a reference to curvature on this page? —Preceding unsigned comment added by 65.199.189.6 ( talk) 15:02, 14 July 2010 (UTC)
"For electromagnetic radiation in vacuum, wavenumber is proportional to frequency and to photon energy." Ok so what about if we're not in vacuum? Apparently when a photon goes from vacuum (index of refraction 1.0) to glass (index of refraction 1.5) the wavenumber would increase by the same amount (1.5 divided by 1.0). Does that imply its energy increased by the same amount? And when it leaves the glass would it lose that energy?
I can't find answers to these questions anywhere on the internet. Odd...
24.162.242.96 ( talk) 13:32, 14 June 2013 (UTC)
The content of this article is largely redundant with the article Wave vector, and would be even more if that article were as well written as this. Wouldn't it be clearer if the two articles were merged? 85.23.38.101 ( talk) 17:34, 2 March 2014 (UTC)
Why is permeability μ0 mentioned in this article? Simon de Danser ( talk) 08:48, 23 November 2016 (UTC)
In the introduction it is currently written
"1 cm−1 of energy is the amount of energy in a single photon with a wavelength of 1 cm"
This seems to imply a linear connection between wavenumber and energy, which is however inverse. I would change it into:
"10 cm−1 of energy is the amount of energy in a single photon with a wavelength of 1/10 cm"
Thoughts?
Further I suggest to link a energy converter, like this one:
130.83.182.68 ( talk) 14:41, 15 February 2017 (UTC)
There is a linear dependence between energy and wavenumber. That is, increased wavenumber corresponds to increased photon energy. Gah4 ( talk) 20:18, 5 April 2018 (UTC)
As well as I know it, wavenumber was used in spectroscopy from the days before an accurate speed of light. Wavenumber can be directly measured with a diffraction grating, so it is more like temporal frequency can be determined from wavenumber, assuming a certain speed of light. Gah4 ( talk) 20:16, 5 April 2018 (UTC)
I suggest removing the 'Definition' section entirely as there are two inconsistent definitions of wavenumber and the current section is mixed up between them. Instead let's just have the two sections "In wave equations" and "In spectroscopy" that each address their own internally consistent logic.
Wavenumber definition 1 (general wave equations):
Wavenumber definition 2 (spectroscopy):
Thoughts? -- Nanite ( talk) 22:06, 5 April 2018 (UTC)
As far as I know, the historical reason for spectroscopy to use wavenumber instead of frequency is that measurements were already more accurate than the known speed of light. In many places, such as acoustics, it is easier to describe waves in terms of frequency, but that wasn't the case here. Only later when the connection through quantum mechanics to photon energy came about, did this distinction become important. Gah4 ( talk) 13:54, 31 October 2018 (UTC)
An editor has asked for a discussion to address the redirect Orders of magnitude (wavenumber). Please participate in the redirect discussion if you wish to do so. Utopes ( talk / cont) 22:54, 7 April 2020 (UTC)
This
level-5 vital article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||
|
I do not agree with the "word" "wavenumber". I think that it ought to be "wave-number" all the way through. The English language does not create new compound words willy-nilly. It is not German.
I've seen the quantitiy "circular wavenumber" referred to as "angular wavenumber". "Angular" seems to be a bit more descriptive and follows the pattern of "angular frequency". (No one says "circular frequency", but language is not always symmetrical or sensible.) Also, Google finds more pages with "angular wavenumber" than "circular wavenumber". Should we retitle the "circular wavenumber" section and mention both quantity names? Zeroparallax 10:54, 17 March 2006 (UTC)
The solutions to a physics HW we had involved what it called the "wavenumber" "k", and it said that:
Does this correspond with anything? I can't find anything about that formula anywhere, and our physics teacher didn't actually teach it to us, although I guess he thinks he did. That and I can't get it to reconcile with de Broiglie's relations. Anyone have any idea what he's talking about? Fresheneesz 06:49, 8 May 2006 (UTC)
In summary, the correct relationship is:
This relationship defines the angular wavenumber of a matter wave (for example an electron) in terms of its mass, its kinetic energy, and Planck's constant (divided by 2 pi). Another correct relationship is:
This relationship defines the angular wavenumber of a matter wave in terms of its momentum and Planck's constant (divided by 2 pi). These relationships hold true for a particle in a box ( quantized angular wavenumbers) or free particle ( continuous angular wavenumbers) because they simply restate the de Broiglie's relations. In fact the page on de Broiglie's relations refers to this article on wavenumber. Therefore the wavenumber article should refer to de Broiglie's relations. The field is quantum mechanics. -- John David Wright 22:29, 23 February 2007 (UTC)
This page need to specify the conversion factors between wavenumbers (cm-1) and Energy/angular frequency, preferably in terms of fundamental constants if that is possible. —Preceding unsigned comment added by 82.35.34.20 ( talk • contribs)
It would be easier to understand the concept if we use plain language appropriate to an encyclopedia. I suggest replacing:
Wavenumber in most physical sciences is a wave property inversely related to wavelength, having SI units of reciprocal meters (m−1).
With:
Wavenumber in most physical sciences is a wave property inversely related to wavelength, having SI units of cycles per unit length or radians per unit length, where the unit length is stated and is typically meters, centimeters, nanometers etc. The dimensions are L-1.
Also:
"The energy corresponds to a wavenumber of 300 reciprocal centimeters (or inverse centimeters or per centimeter)"
would be more clearly: "The energy corresponds to a wavenumber of 300 cycles per centimeter"
Any comments?
GilesW (
talk)
07:30, 22 April 2009 (UTC)
In the context of RF coils etc., please define "radial wavenumber". It is said to be "all important" [ [1]], (see second page between expressions (3) and (4)). I cannot find a definition. GilesW ( talk) 07:56, 8 May 2009 (UTC)
In this edit, physicist User:Dicklyon threw the whole article around, calling spectroscopy an oddball field. But to hosts of chemists and biologists, wavenumbers has no other meaning than a unit of energy. The lead of this article now ignores that. It only explains this term as angular wavenumber, which is the magnitude of the wave vector, of relevance only to physicists that should already know what this is anyway. The article should aim at the general reader, which is someone who wants to know what it means that a " Raman peak is at 300 wavenumbers". / Pieter Kuiper ( talk) 07:41, 24 March 2010 (UTC)
This edit:
http://en.wikipedia.org/?title=Wavenumber&diff=prev&oldid=33599618
seems inconsistent with . The equation, as it presently appears, is:
but should (I think) be:
Comments? —Preceding unsigned comment added by 70.234.243.222 ( talk) 02:14, 11 April 2010 (UTC)
I was curious as to what the connection is between wave number and curvature. Why would you have a reference to curvature on this page? —Preceding unsigned comment added by 65.199.189.6 ( talk) 15:02, 14 July 2010 (UTC)
"For electromagnetic radiation in vacuum, wavenumber is proportional to frequency and to photon energy." Ok so what about if we're not in vacuum? Apparently when a photon goes from vacuum (index of refraction 1.0) to glass (index of refraction 1.5) the wavenumber would increase by the same amount (1.5 divided by 1.0). Does that imply its energy increased by the same amount? And when it leaves the glass would it lose that energy?
I can't find answers to these questions anywhere on the internet. Odd...
24.162.242.96 ( talk) 13:32, 14 June 2013 (UTC)
The content of this article is largely redundant with the article Wave vector, and would be even more if that article were as well written as this. Wouldn't it be clearer if the two articles were merged? 85.23.38.101 ( talk) 17:34, 2 March 2014 (UTC)
Why is permeability μ0 mentioned in this article? Simon de Danser ( talk) 08:48, 23 November 2016 (UTC)
In the introduction it is currently written
"1 cm−1 of energy is the amount of energy in a single photon with a wavelength of 1 cm"
This seems to imply a linear connection between wavenumber and energy, which is however inverse. I would change it into:
"10 cm−1 of energy is the amount of energy in a single photon with a wavelength of 1/10 cm"
Thoughts?
Further I suggest to link a energy converter, like this one:
130.83.182.68 ( talk) 14:41, 15 February 2017 (UTC)
There is a linear dependence between energy and wavenumber. That is, increased wavenumber corresponds to increased photon energy. Gah4 ( talk) 20:18, 5 April 2018 (UTC)
As well as I know it, wavenumber was used in spectroscopy from the days before an accurate speed of light. Wavenumber can be directly measured with a diffraction grating, so it is more like temporal frequency can be determined from wavenumber, assuming a certain speed of light. Gah4 ( talk) 20:16, 5 April 2018 (UTC)
I suggest removing the 'Definition' section entirely as there are two inconsistent definitions of wavenumber and the current section is mixed up between them. Instead let's just have the two sections "In wave equations" and "In spectroscopy" that each address their own internally consistent logic.
Wavenumber definition 1 (general wave equations):
Wavenumber definition 2 (spectroscopy):
Thoughts? -- Nanite ( talk) 22:06, 5 April 2018 (UTC)
As far as I know, the historical reason for spectroscopy to use wavenumber instead of frequency is that measurements were already more accurate than the known speed of light. In many places, such as acoustics, it is easier to describe waves in terms of frequency, but that wasn't the case here. Only later when the connection through quantum mechanics to photon energy came about, did this distinction become important. Gah4 ( talk) 13:54, 31 October 2018 (UTC)
An editor has asked for a discussion to address the redirect Orders of magnitude (wavenumber). Please participate in the redirect discussion if you wish to do so. Utopes ( talk / cont) 22:54, 7 April 2020 (UTC)