![]() | This ![]() It is of interest to the following WikiProjects: | ||||||||||||||||||||
|
![]() | A fact from Fourier-transform infrared spectroscopy appeared on Wikipedia's
Main Page in the
Did you know column on 14 August 2010 (
check views). The text of the entry was as follows:
| ![]() |
![]() | This article links to one or more target anchors that no longer exist.
Please help fix the broken anchors. You can remove this template after fixing the problems. |
Reporting errors |
It states what the difference is between it and standard spectroscopy (lots of colours at once and in various different patterns), but not why you'd want to do that. —Preceding unsigned comment added by 82.24.47.178 ( talk) 00:57, 19 August 2010 (UTC)
Reflectance (ATR) is also important. There are pictures of ATR devices in Wiki commons, but in FTIR a cylindrical rather than a flat crystal is used. I didn't think it worth going into so much technical detail. Petergans ( talk) 21:05, 1 August 2010 (UTC)
Secondly, I don't think that the illustrated interferogram is real. It looks like a sinc function which would imply a monochromatic source. Petergans ( talk) 21:27, 1 August 2010 (UTC)
I've just looked at Frustrated total internal reflection. I believe that this is the same as ATR. Some general clean-up is needed. I don't think that the link as it stands is helpful. Petergans ( talk) 08:48, 2 August 2010 (UTC)
Another point. "while a disadvantage is that FTIR cannot use as sensitive a detector as dispersive measurements can". I wonder if this is any longer true. See Mercury cadmium telluride#infrared detection. Petergans ( talk) 15:09, 2 August 2010 (UTC) Also mct vs DTGS comparison
There should be a section on detectors. Can anyone help? I created a stub on triglycine sulfate which, amazingly, was (as of 5 Aug 2010) not even mentioned in infrared detector. An important point is that PbS and related detectors are useful in NIR and are often available in UV/Vis spectrometers with a wavelength range that extends into the NIR. Petergans ( talk) 16:30, 5 August 2010 (UTC)
I think there is an error in the plot of the interferogram: Since the axis is labeled Intensity negative values make no sense. I have seen a different version of this plot in one of my lectures with the center of the axis being 0.5, which, in my opinion would make more sense —Preceding unsigned comment added by 78.142.92.52 ( talk) 20:18, 5 January 2011 (UTC)
In the section "far-infrared FTIR" there is the phrase "For the relatively long wavelengths of the far infrared (~10 μm), tolerances are adequate, whereas for the rock-salt region tolerances have to be better than 1 μm."
What the heck is the 'rock-salt region'??? This is used again in the mid-IR section. I've read mainly about thermal and near-IR FTIR, but I've never heard this term, and a google search shows up mainly this article and copies of it. Is this a real term? -- snheath@gmail.com (6 April 2011)
I just replaced the interferogram image (from File:Ftir-interferogramEn.png to File:FTIR-interferogram.svg). I took this one myself, so there is no question that it is a real interferogram from a real FTIR machine (unlike the previous one). I'm happy to edit the image if there are any suggestions :-) -- Steve ( talk) 04:54, 11 June 2011 (UTC)
I made this change, reverting an edit by 7homas.martin to the version I had originally written.
7homas.martin, you said that my version had a "mistake about how the Michelson interferometer works", but I see no mistake. Can you tell me what the mistake is?
The reason I like my version better is that I think it is clearer as an introduction for someone who was previously unfamiliar with anything about FTIRs. For example, 7homas's version says "The light shines into a certain configuration of mirrors, called a Michelson interferometer, that allows to record an interferogram as the mirror is moving (due to wave interference)." The way this sentence is written, the reader is assumed to already know what an interferogram is. Most readers do not. The next sentence says "The interferogram is the mathematical equivalent of the spectrum", which is misleading and confusing. The meaning of "mathematical equivalent" is not obvious, even to a mathematician. I assume that 7homas means to say something like "The interferogram contains the same information as the spectrum and can be transformed into the spectrum." But a reader will understand this sentence as meaning something like "The interferogram is the same as the spectrum", which is not correct. I don't know whether they are "mathematically equivalent" when they are different functions, with different ranges, resolutions, noise properties, etc. I would say they are "fourier transforms of each other", but I would not say they are "mathematically equivalent to each other" without any more specifics about what I mean by that.
I just went through the first two sentences as an example. Like these, I found that all the changes were making things more confusing, especially for people who are not already experts on the subject of FTIRs. Therefore I changed it back.
Now that I've explained what I dislike about your version, 7homas, you can explain what you found confusing or misleading or incorrect about my wording! Hopefully we will wind up with something we can all agree on. :-) -- Steve ( talk) 13:26, 5 October 2012 (UTC)
OK, this is helpful. My original wording omitted the word "filter" and I am happy to continue avoiding it (even though I personally think it's not misleading). Your suggestion seems problematic to me because the term "interference pattern" evokes something quite different. Some people do not know what an "interference pattern" is at all, but the rest will almost definitely be imagining an interference pattern in space. For example, I did a google image search for "interference pattern", and all the results were things like this, i.e. two-slit interference. As an FTIR scans, there is never this kind of "interference pattern" in the output: At every moment, the cross section of the beam is spatially uniform in both spectrum and intensity (assuming the FTIR is properly apertured). The oscillatory "pattern" only emerges in an abstract graph, like a graph of the spectrum at a given moment, or the interferogram plot. So "interference pattern" is evoking a misleading image.
Back to my old wording, I said:
The light shines into a certain configuration of mirrors, called a Michelson interferometer, that allows some wavelengths to pass through but blocks others (due to wave interference). The beam is modified for each new data point by moving one of the mirrors; this changes the set of wavelengths that pass through.
I could be wrong, but I think your objection stems from the fact that I did not clearly distinguish "the Michelson interferometer at any given moment, i.e. with a certain mirror configuration" from "the Michelson interferometer as the mirror is scanned". In the first sentence, I meant the former, but you read it as the latter, and I get the impression that you're not accustomed to thinking about the former at all. So let me try to improve...
The light shines into a Michelson interferometer—a certain configuration of mirrors, one of which is moved by a motor. As this mirror moves, each wavelength of light in the beam is periodically blocked, transmitted, blocked, transmitted, by the interferometer, due to wave interference. Different wavelengths are modulated at different rates, so that at each moment, the beam coming out of the interferometer has a different spectrum.
Does that help? :-) -- Steve ( talk) 19:14, 10 October 2012 (UTC)
That's really better, thanks :). The fact that it does not work as a simple filter is more clear this way. -- 7homas.martin ( talk) 19:46, 10 October 2012 (UTC)
I've not read all through the rambling discussion above. It seems to be missing the point. The Michelson interferometer works by modulating the light from a "white" light source. The modulated light is passed through the sample, which absobs at specific wavelengths by specific amounts. The light is then demodulated to give back the spectrum of the original source, minus some intensity at wavelengths absorbed. The spectrum of the sample is obtained by removing the spectrum of the source (ratio-ing). The principal advantage of this procedure is that light intensity is measured at all wavelengths simultaneously. In the same way, astronomical measurements of emission spectra are collected at all wavelengths by passing the starlight through an interferometer, recording the intensity as a function of retardation, and then FT to recover the spectrum. In fact I believe that the interferometer was first developed for astronomy (Connes) and only later for ir spectroscopy.
More technically, mirror movement produces, by mechanical means, a Fourier transform of the spectrum of the source from the wavelength domain to the distance co-domain. The Fourier transform of the interferogram returns the data back to the wavelength domain. Petergans ( talk) 13:30, 2 November 2012 (UTC)
I have a discussion type explanation of "The Basic Concept"
Imagine an oscilloscope screen shot of an audio recording containing many frequencies. Imagine a jumble of waves and wiggles. The signal can be digitized, and the fourier transform can be applied to create an Intensity versus Frequency graph.
I will take it for granted, that using Fourier Transform calculations, the raw signal from an audio microphone can be converted to a spectrum of frequencies. by digitizing the incoming signal, for a group of frequencies, that are, say 1MegaHertz and under.
The problem with Infrared frequencies, is that, first our detectors do not create an electrical wave corresponding to the very high frequency waves in the terahertz range. Also, in the current state of the art of digitizing a waveform, I think 100 Giga Samples per second is very difficult to pull off.
The incoming IR light signals, coming in with frequencies in the TeraHertz range, would be impossible to directly convert to an electrical signal, and then digitize it, at such fast frequencies.
The Michelson interferometry arrangement with a moveable mirror performs an essential function of converting an incoming Infrared frequency into a much lower corresponding Audio range frequency.
For example: Imagine a source emitting a single IR frequency, say one with a frequency of 3 TeraHertz, with a wavelength of:(Speed of light)/(number of waves) = (3.00x10exp13 mm/sec)/(3x10exp12 waves/sec) = 1mm
Now, in the interferometry setup with the moving mirror, let us choose a mirror moving at 1 cm/sec. This changes the travel distance, so after one second moving away, the new light beam has to travel an extra cm going to the mirror, as well as an extra cm, coming back from the mirror. When this beam is recombined with it's split copy, that did not change path length, there is a total of 2 cm containing 20 waves with length 1mm, which would constructively, and destructively interfere creating a sequence of dark and light cycles arriving at the IR detector at a rate of 20 Hz. So we see that the FTIR mirror setup will convert an originally 3 Thz wave into a 20 Htz wave. Likewise, if we study a 300 Terahertz wave, it will be converted to a 2000 Hz wave. Waves such as these are in the audio frequency range, in fact, if the raw signal from the FTIR detector was hooked to an amplified speaker, we could 'hear' the FTIR spectrum with our ears. But the point I wish to make, is that it is easy to see how the Fourier transform can now be done on this converted set of frequencies, to create the Intensity .vs. frequency graph, typical of what we take for granted, when using a modern digital oscilloscope, to analyze a raw scope probe signal.
In summary, I am taking it as a leap of faith, as to how the Fourier transform actually does its magic, of converting a raw signal into one that is a graph of intensity .vs. frequency. I AM pointing out that the arrangement of the moving and stationary mirrors within the FTIR instrument, can be thought of as converting the high TeraHertz range frequencies of IR waves, and converting them to a much lower 'Audio' range frequency, with each IR frequency having a calculated value in the lower frequency detected by the FTIR detector.
Thank you for considering this and I hope it adds some insight into how the FTIR works.
Bunrabbit ( talk) 07:00, 27 May 2014 (UTC)
Our Professor told us, that you have to make for a better resolution either the way of the mirror longer or the part of the spectrum smaller, you are measuring. Can anyone explain me why - and add it after in the article? I couldn't find it in any book... Thx! -- Minihaa ( talk) 13:52, 24 January 2013 (UTC)
The interferometer diagram shows a "coherent light source." In the case of the FTIR, the light entering the interferometer is definitely not coherent. Otherwise, you wouldn't need an FT, you'd have a scanning dispersive spec. — Preceding unsigned comment added by Cyclotronics ( talk • contribs) 14:29, 13 May 2014 (UTC)
For me the mathematical derivation (one page) helped a lot. Someone should add it! I may add it later if I have time. It can be found on pg 7 here: [1] Danski14 (talk) 03:39, 25 March 2015 (UTC)
Other issue: there seems to be an error in the section "Isotope effects" there: "The reduced masses for 16O–16O and 18O–18O can be approximated as 8 and 9 respectively." One line above the rediced mass is defined. The (quite common) expression yields 0.5 if mA = mB, so I fail to see how it should evaluate to 8 or 9. The latter value probably already includes the spring constant k. — Preceding unsigned comment added by 134.130.27.17 ( talk) 12:50, 26 September 2016 (UTC)
The result of the move request was: Keep the hyphenated title. Steve ( talk) 14:16, 19 August 2017 (UTC)
Fourier-transform infrared spectroscopy → Fourier transform infrared spectroscopy – Mikhail Ryazanov ( talk · contribs) has changed the page name from "Fourier transform infrared spectroscopy" to "Fourier-transform infrared spectroscopy" citing MOS:HYPHEN. I propose to change it back. I think that whatever MOS:HYPHEN says is trumped by WP:TITLE: "Generally, article titles are based on what the subject is called in reliable sources." I have seen it written "Fourier transform infrared spectroscopy" in countless books, articles, vendor websites, course notes, etc. etc. I have never seen it written "Fourier-transform infrared spectroscopy" as far as I can remember. Wikipedia needs to write the term the way everyone else writes it. So I propose to move the page back. What do other people think? (Note: I opened this conversation on 11 August 2017 but didn't add the template until the 17th.) Steve ( talk) 01:31, 17 August 2017 (UTC)
Hello fellow Wikipedians,
I have just modified one external link on Fourier-transform infrared spectroscopy. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
This message was posted before February 2018.
After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than
regular verification using the archive tool instructions below. Editors
have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
RfC before doing mass systematic removals. This message is updated dynamically through the template {{
source check}}
(last update: 5 June 2024).
Cheers.— InternetArchiveBot ( Report bug) 23:51, 4 October 2017 (UTC)
The following Wikimedia Commons file used on this page has been nominated for speedy deletion:
You can see the reason for deletion at the file description page linked above. — Community Tech bot ( talk) 21:21, 10 June 2019 (UTC)
I think the "clarification needed" tag in the "Measuring and processing the interferogram" section is adequately addressed through the Aliasing article wikilink; unless there are objections, I'll remove it next week. -- Ironphoenix ( talk) 17:12, 26 August 2023 (UTC) (Done!) -- Ironphoenix ( talk) 14:29, 2 September 2023 (UTC)
![]() | This ![]() It is of interest to the following WikiProjects: | ||||||||||||||||||||
|
![]() | A fact from Fourier-transform infrared spectroscopy appeared on Wikipedia's
Main Page in the
Did you know column on 14 August 2010 (
check views). The text of the entry was as follows:
| ![]() |
![]() | This article links to one or more target anchors that no longer exist.
Please help fix the broken anchors. You can remove this template after fixing the problems. |
Reporting errors |
It states what the difference is between it and standard spectroscopy (lots of colours at once and in various different patterns), but not why you'd want to do that. —Preceding unsigned comment added by 82.24.47.178 ( talk) 00:57, 19 August 2010 (UTC)
Reflectance (ATR) is also important. There are pictures of ATR devices in Wiki commons, but in FTIR a cylindrical rather than a flat crystal is used. I didn't think it worth going into so much technical detail. Petergans ( talk) 21:05, 1 August 2010 (UTC)
Secondly, I don't think that the illustrated interferogram is real. It looks like a sinc function which would imply a monochromatic source. Petergans ( talk) 21:27, 1 August 2010 (UTC)
I've just looked at Frustrated total internal reflection. I believe that this is the same as ATR. Some general clean-up is needed. I don't think that the link as it stands is helpful. Petergans ( talk) 08:48, 2 August 2010 (UTC)
Another point. "while a disadvantage is that FTIR cannot use as sensitive a detector as dispersive measurements can". I wonder if this is any longer true. See Mercury cadmium telluride#infrared detection. Petergans ( talk) 15:09, 2 August 2010 (UTC) Also mct vs DTGS comparison
There should be a section on detectors. Can anyone help? I created a stub on triglycine sulfate which, amazingly, was (as of 5 Aug 2010) not even mentioned in infrared detector. An important point is that PbS and related detectors are useful in NIR and are often available in UV/Vis spectrometers with a wavelength range that extends into the NIR. Petergans ( talk) 16:30, 5 August 2010 (UTC)
I think there is an error in the plot of the interferogram: Since the axis is labeled Intensity negative values make no sense. I have seen a different version of this plot in one of my lectures with the center of the axis being 0.5, which, in my opinion would make more sense —Preceding unsigned comment added by 78.142.92.52 ( talk) 20:18, 5 January 2011 (UTC)
In the section "far-infrared FTIR" there is the phrase "For the relatively long wavelengths of the far infrared (~10 μm), tolerances are adequate, whereas for the rock-salt region tolerances have to be better than 1 μm."
What the heck is the 'rock-salt region'??? This is used again in the mid-IR section. I've read mainly about thermal and near-IR FTIR, but I've never heard this term, and a google search shows up mainly this article and copies of it. Is this a real term? -- snheath@gmail.com (6 April 2011)
I just replaced the interferogram image (from File:Ftir-interferogramEn.png to File:FTIR-interferogram.svg). I took this one myself, so there is no question that it is a real interferogram from a real FTIR machine (unlike the previous one). I'm happy to edit the image if there are any suggestions :-) -- Steve ( talk) 04:54, 11 June 2011 (UTC)
I made this change, reverting an edit by 7homas.martin to the version I had originally written.
7homas.martin, you said that my version had a "mistake about how the Michelson interferometer works", but I see no mistake. Can you tell me what the mistake is?
The reason I like my version better is that I think it is clearer as an introduction for someone who was previously unfamiliar with anything about FTIRs. For example, 7homas's version says "The light shines into a certain configuration of mirrors, called a Michelson interferometer, that allows to record an interferogram as the mirror is moving (due to wave interference)." The way this sentence is written, the reader is assumed to already know what an interferogram is. Most readers do not. The next sentence says "The interferogram is the mathematical equivalent of the spectrum", which is misleading and confusing. The meaning of "mathematical equivalent" is not obvious, even to a mathematician. I assume that 7homas means to say something like "The interferogram contains the same information as the spectrum and can be transformed into the spectrum." But a reader will understand this sentence as meaning something like "The interferogram is the same as the spectrum", which is not correct. I don't know whether they are "mathematically equivalent" when they are different functions, with different ranges, resolutions, noise properties, etc. I would say they are "fourier transforms of each other", but I would not say they are "mathematically equivalent to each other" without any more specifics about what I mean by that.
I just went through the first two sentences as an example. Like these, I found that all the changes were making things more confusing, especially for people who are not already experts on the subject of FTIRs. Therefore I changed it back.
Now that I've explained what I dislike about your version, 7homas, you can explain what you found confusing or misleading or incorrect about my wording! Hopefully we will wind up with something we can all agree on. :-) -- Steve ( talk) 13:26, 5 October 2012 (UTC)
OK, this is helpful. My original wording omitted the word "filter" and I am happy to continue avoiding it (even though I personally think it's not misleading). Your suggestion seems problematic to me because the term "interference pattern" evokes something quite different. Some people do not know what an "interference pattern" is at all, but the rest will almost definitely be imagining an interference pattern in space. For example, I did a google image search for "interference pattern", and all the results were things like this, i.e. two-slit interference. As an FTIR scans, there is never this kind of "interference pattern" in the output: At every moment, the cross section of the beam is spatially uniform in both spectrum and intensity (assuming the FTIR is properly apertured). The oscillatory "pattern" only emerges in an abstract graph, like a graph of the spectrum at a given moment, or the interferogram plot. So "interference pattern" is evoking a misleading image.
Back to my old wording, I said:
The light shines into a certain configuration of mirrors, called a Michelson interferometer, that allows some wavelengths to pass through but blocks others (due to wave interference). The beam is modified for each new data point by moving one of the mirrors; this changes the set of wavelengths that pass through.
I could be wrong, but I think your objection stems from the fact that I did not clearly distinguish "the Michelson interferometer at any given moment, i.e. with a certain mirror configuration" from "the Michelson interferometer as the mirror is scanned". In the first sentence, I meant the former, but you read it as the latter, and I get the impression that you're not accustomed to thinking about the former at all. So let me try to improve...
The light shines into a Michelson interferometer—a certain configuration of mirrors, one of which is moved by a motor. As this mirror moves, each wavelength of light in the beam is periodically blocked, transmitted, blocked, transmitted, by the interferometer, due to wave interference. Different wavelengths are modulated at different rates, so that at each moment, the beam coming out of the interferometer has a different spectrum.
Does that help? :-) -- Steve ( talk) 19:14, 10 October 2012 (UTC)
That's really better, thanks :). The fact that it does not work as a simple filter is more clear this way. -- 7homas.martin ( talk) 19:46, 10 October 2012 (UTC)
I've not read all through the rambling discussion above. It seems to be missing the point. The Michelson interferometer works by modulating the light from a "white" light source. The modulated light is passed through the sample, which absobs at specific wavelengths by specific amounts. The light is then demodulated to give back the spectrum of the original source, minus some intensity at wavelengths absorbed. The spectrum of the sample is obtained by removing the spectrum of the source (ratio-ing). The principal advantage of this procedure is that light intensity is measured at all wavelengths simultaneously. In the same way, astronomical measurements of emission spectra are collected at all wavelengths by passing the starlight through an interferometer, recording the intensity as a function of retardation, and then FT to recover the spectrum. In fact I believe that the interferometer was first developed for astronomy (Connes) and only later for ir spectroscopy.
More technically, mirror movement produces, by mechanical means, a Fourier transform of the spectrum of the source from the wavelength domain to the distance co-domain. The Fourier transform of the interferogram returns the data back to the wavelength domain. Petergans ( talk) 13:30, 2 November 2012 (UTC)
I have a discussion type explanation of "The Basic Concept"
Imagine an oscilloscope screen shot of an audio recording containing many frequencies. Imagine a jumble of waves and wiggles. The signal can be digitized, and the fourier transform can be applied to create an Intensity versus Frequency graph.
I will take it for granted, that using Fourier Transform calculations, the raw signal from an audio microphone can be converted to a spectrum of frequencies. by digitizing the incoming signal, for a group of frequencies, that are, say 1MegaHertz and under.
The problem with Infrared frequencies, is that, first our detectors do not create an electrical wave corresponding to the very high frequency waves in the terahertz range. Also, in the current state of the art of digitizing a waveform, I think 100 Giga Samples per second is very difficult to pull off.
The incoming IR light signals, coming in with frequencies in the TeraHertz range, would be impossible to directly convert to an electrical signal, and then digitize it, at such fast frequencies.
The Michelson interferometry arrangement with a moveable mirror performs an essential function of converting an incoming Infrared frequency into a much lower corresponding Audio range frequency.
For example: Imagine a source emitting a single IR frequency, say one with a frequency of 3 TeraHertz, with a wavelength of:(Speed of light)/(number of waves) = (3.00x10exp13 mm/sec)/(3x10exp12 waves/sec) = 1mm
Now, in the interferometry setup with the moving mirror, let us choose a mirror moving at 1 cm/sec. This changes the travel distance, so after one second moving away, the new light beam has to travel an extra cm going to the mirror, as well as an extra cm, coming back from the mirror. When this beam is recombined with it's split copy, that did not change path length, there is a total of 2 cm containing 20 waves with length 1mm, which would constructively, and destructively interfere creating a sequence of dark and light cycles arriving at the IR detector at a rate of 20 Hz. So we see that the FTIR mirror setup will convert an originally 3 Thz wave into a 20 Htz wave. Likewise, if we study a 300 Terahertz wave, it will be converted to a 2000 Hz wave. Waves such as these are in the audio frequency range, in fact, if the raw signal from the FTIR detector was hooked to an amplified speaker, we could 'hear' the FTIR spectrum with our ears. But the point I wish to make, is that it is easy to see how the Fourier transform can now be done on this converted set of frequencies, to create the Intensity .vs. frequency graph, typical of what we take for granted, when using a modern digital oscilloscope, to analyze a raw scope probe signal.
In summary, I am taking it as a leap of faith, as to how the Fourier transform actually does its magic, of converting a raw signal into one that is a graph of intensity .vs. frequency. I AM pointing out that the arrangement of the moving and stationary mirrors within the FTIR instrument, can be thought of as converting the high TeraHertz range frequencies of IR waves, and converting them to a much lower 'Audio' range frequency, with each IR frequency having a calculated value in the lower frequency detected by the FTIR detector.
Thank you for considering this and I hope it adds some insight into how the FTIR works.
Bunrabbit ( talk) 07:00, 27 May 2014 (UTC)
Our Professor told us, that you have to make for a better resolution either the way of the mirror longer or the part of the spectrum smaller, you are measuring. Can anyone explain me why - and add it after in the article? I couldn't find it in any book... Thx! -- Minihaa ( talk) 13:52, 24 January 2013 (UTC)
The interferometer diagram shows a "coherent light source." In the case of the FTIR, the light entering the interferometer is definitely not coherent. Otherwise, you wouldn't need an FT, you'd have a scanning dispersive spec. — Preceding unsigned comment added by Cyclotronics ( talk • contribs) 14:29, 13 May 2014 (UTC)
For me the mathematical derivation (one page) helped a lot. Someone should add it! I may add it later if I have time. It can be found on pg 7 here: [1] Danski14 (talk) 03:39, 25 March 2015 (UTC)
Other issue: there seems to be an error in the section "Isotope effects" there: "The reduced masses for 16O–16O and 18O–18O can be approximated as 8 and 9 respectively." One line above the rediced mass is defined. The (quite common) expression yields 0.5 if mA = mB, so I fail to see how it should evaluate to 8 or 9. The latter value probably already includes the spring constant k. — Preceding unsigned comment added by 134.130.27.17 ( talk) 12:50, 26 September 2016 (UTC)
The result of the move request was: Keep the hyphenated title. Steve ( talk) 14:16, 19 August 2017 (UTC)
Fourier-transform infrared spectroscopy → Fourier transform infrared spectroscopy – Mikhail Ryazanov ( talk · contribs) has changed the page name from "Fourier transform infrared spectroscopy" to "Fourier-transform infrared spectroscopy" citing MOS:HYPHEN. I propose to change it back. I think that whatever MOS:HYPHEN says is trumped by WP:TITLE: "Generally, article titles are based on what the subject is called in reliable sources." I have seen it written "Fourier transform infrared spectroscopy" in countless books, articles, vendor websites, course notes, etc. etc. I have never seen it written "Fourier-transform infrared spectroscopy" as far as I can remember. Wikipedia needs to write the term the way everyone else writes it. So I propose to move the page back. What do other people think? (Note: I opened this conversation on 11 August 2017 but didn't add the template until the 17th.) Steve ( talk) 01:31, 17 August 2017 (UTC)
Hello fellow Wikipedians,
I have just modified one external link on Fourier-transform infrared spectroscopy. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
This message was posted before February 2018.
After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than
regular verification using the archive tool instructions below. Editors
have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
RfC before doing mass systematic removals. This message is updated dynamically through the template {{
source check}}
(last update: 5 June 2024).
Cheers.— InternetArchiveBot ( Report bug) 23:51, 4 October 2017 (UTC)
The following Wikimedia Commons file used on this page has been nominated for speedy deletion:
You can see the reason for deletion at the file description page linked above. — Community Tech bot ( talk) 21:21, 10 June 2019 (UTC)
I think the "clarification needed" tag in the "Measuring and processing the interferogram" section is adequately addressed through the Aliasing article wikilink; unless there are objections, I'll remove it next week. -- Ironphoenix ( talk) 17:12, 26 August 2023 (UTC) (Done!) -- Ironphoenix ( talk) 14:29, 2 September 2023 (UTC)