Why Raman spectroscope doesn't use 532nm laser ?.

[NEETZGr8]

Most of the commercial Raman spectrometer uses 785nm or IR laser as excitation source. Though we could use visible lasers like 532 nm in this place, which can reduce the overall cost of the device by

1. Using less power laser( since intensity of raman signal is inversly propotional to the 4th power of wavelength)
2. use silicon ccd detectors, which are less costly compared to the InGAs IR detector
3. No need of detector cooling mechanism

Only issue with 532 nm is the interfernce from fluroscence, which can be removed using proper background subtraction in post data acquisiton.
Then still why 532 nm lasers is not being used in raman spectrometers, especially in hand held raman spectrometer?. Is there any specific reason for not using 532 nm.
Could someone help me with this.

 

[HAYAO]

I don't work with Raman spectroscopy but like you said, the usual convention is to avoid fluorescence, especially for organic molecules. I don't think "less power laser" is necessarily true. It largely depends on what kind of laser you are using, but if you are thinking diode lasers, then it generally requires more power to use diode lasers with shorter wavelength than longer wavelength to produce the same number of photons.

There are indeed cases where you want resonance Raman, or working with inorganic material that have significantly larger band gap than organic molecules, or sometimes require better spatial resolution. Then you need different sources.