This is how the 4000 cm-1 come out from the 532nm Raman spectrometer.microb wrote: ↑Fri Nov 20, 2020 12:12 pmI've read that too, and like a bad manual that spends pages on how to plug the product into an outlet, the details on the internet on this are lacking. And I assume it's not actually complicated, but no one's willing to write it down anywhere.Scarodactyl wrote: ↑Fri Nov 20, 2020 6:58 amRaman spectroscopy looks at the shift between the input wavelength and what bounces back, which is independent of input wavelength. So what you're graphing is the spectrum of the raman shift in inverse centimeters.
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)
I used this url to convert between nm and cm-1
532nm = 18796.99 cm-1
18796.99 cm-1 – 4000 cm-1
14797cm-1 = 675.81nm
So my Raman system has range of 532nm to 675.81nm giving difference of 4000 cm-1
It can only measure strokes shift. A strokes shift is lower in frequency so higher in wavelength hence 532nm to 675.81nm and not lower.
My raman has converging laser focused 20mm from front of lens. Does anyone know what kind of lens I should use to convert it to parallel (or whatever required by microscope)? so it can be used in a transmitted microscope? And what is the least expensive transmissive microscope I can insert the parallel laser (after it becomes parallel via some kind of lens)?
Also a Raman setup has simple parts. Mine has the above parts too. How can it cost $15000? Maybe the parts cost only $1000 or less? What you think? Even though I own a Raman. I'm still a beginner in it.