Raman Spectrometer 1um to 20um IR

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microb
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Joined: Wed Mar 27, 2019 6:39 am

Raman Spectrometer 1um to 20um IR

#1 Post by microb » Thu Nov 19, 2020 8:31 pm

What sensors are used for a Raman spectrometer to get data in situ for the longer frequencies?

A chip like the TCD1304AP gets 300nm ~ 1100nm.

There are some chips I found that go to 3000nm (3um). (https://www.hamamatsu.com/resources/pdf ... r1032e.pdf)

The only other way seems to be using a single point sensor and motored grating. Then check temperature change. (https://www.infratec-infrared.com/senso ... detectors/)

But some products seem to have a linear sensor somehow.

microb
Posts: 729
Joined: Wed Mar 27, 2019 6:39 am

Re: Raman Spectrometer 1um to 20um IR

#2 Post by microb » Fri Nov 20, 2020 6:57 pm

microb wrote:
Thu Nov 19, 2020 8:31 pm
What sensors are used for a Raman spectrometer to get data in situ for the longer frequencies?

A chip like the TCD1304AP gets 300nm ~ 1100nm.

There are some chips I found that go to 3000nm (3um). (https://www.hamamatsu.com/resources/pdf ... r1032e.pdf)

The only other way seems to be using a single point sensor and motored grating. Then check temperature change. (https://www.infratec-infrared.com/senso ... detectors/)

But some products seem to have a linear sensor somehow.
So found my answer, so I'll post it here:

Apparently a normal spectrometer can be used.

But if I have n samples 200nm to 800nm, and the laser let's say at 532nm plus or minus 10nm of data is ignored, the Raman graph has to involve manipulating (intensity,nm) pairs. So it appears we're just going to re-order the nm's and keep the intensities at the same levels.

The graphs are normally 0 to 4000.

Ok, so I found a posting to answer the above:

"As for data processing, one starts by converting the laser wavelength to wavenumbers. I use a simple trick: wavenumbers (cm-1) = 1e7 / wavelength (nm). Say your laser is at 532nm. Converting that to wavenumbers: laser wavenumber = 1e7/532 = 18797 (cm-1). Now using that same formula convert all the other wavelength data over to wavenumbers. In a final step, subtract all the wavenumbers of the spectrum data from the laser wavelength wavenumber. All the data that falls on the positive side of zero are the Stokes line data. All the data that falls on the negative side of zero are the anti-Stokes line data. One normally drops the anti-Stokes data, but not always. Normally, the wavenumber data are displayed on a 0 to 4000 cm-1 scale, similar to a standard IR spectrum.
Now you have a vibrational spectrum (similar to an IR spectrum) where the peaks are in terms of wavenumber shift from the excitation (the laser). Hence one often speaks of the "Raman shift" of a vibrational line."
(https://www.researchgate.net/post/How-t ... er-instead)

stevelev1
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Joined: Mon Apr 19, 2021 1:01 am

Re: Raman Spectrometer 1um to 20um IR

#3 Post by stevelev1 » Mon Apr 19, 2021 1:10 am

Do you know of a way (hopefully not too expensive) that I can attach an infrared spectrometer (including a slit and diffraction grating) to the vertical tube of a trinocular microscope along with a digital camera and associated software that can produce the infrared spectra of the specimen being viewed through the binocular eyepiece? This allows identification and study of the elements and molecular components (infrared vibrational spectra) of a specific portion of the specimen. The field of microspectrophotometry is facinating but the mainstream instruments are prohibitively expensive for the individual amateur microscopist.

microb
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Joined: Wed Mar 27, 2019 6:39 am

Re: Raman Spectrometer 1um to 20um IR

#4 Post by microb » Mon Apr 19, 2021 3:22 am

stevelev1 wrote:
Mon Apr 19, 2021 1:10 am
Do you know of a way (hopefully not too expensive) that I can attach an infrared spectrometer (including a slit and diffraction grating) to the vertical tube of a trinocular microscope along with a digital camera and associated software that can produce the infrared spectra of the specimen being viewed through the binocular eyepiece? This allows identification and study of the elements and molecular components (infrared vibrational spectra) of a specific portion of the specimen. The field of microspectrophotometry is facinating but the mainstream instruments are prohibitively expensive for the individual amateur microscopist.
Can your spectrometer take a fiber cable? Or are you indicating that you are building a spectrometer? If you want a real answer, I think you want to post some pictures of what you have. Otherwise, the most general answer is 3D printing to prototype things.

Basically, you want to do FTIR.

Also the view through the eye piece with an IR light source sounds bad. Hopefully you are using a camera. The camera will have an IR window in front of the sensor.

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