Why make a 785 nm wavelength preferably to be used in Raman spectra ?
Not sure if that answers your question, the linked article gives some explanations for the use of 785 nm:
https://www.laserfocusworld.com/articles/print/volume-36/issue-9/departments/design-and-applications/785-nm-laser-benefits-raman-spectroscopy.html
Dear Colleague Karsten Fleischer,
thank for this useful reply.
Regard
Raad
Dear colleague, generally we should match the wavelenght of the exciting light source for the sample and material which we want to study. Yes, the shorter the wavelenght is the higher is the scattering intensity (~ omega^4). And yes, the shorter the wavelenght is the higher is the probability to excite unwanted luminescence. And don`t forget possible resonance effects. In the case of solid states you should take into account one additional point. The absorption depends also on the wavelength. The shorter the wavelength is the smaller is the penetration depth of the light into the sample, i. e. the smaller is the information depth. If you want to study thin layers on a substrate you should choose a short wavelength. If you want to study bulk properties you need a more larger wavelenght. And finally you have to check the characteristics of your measurement system, i. e. the optimum range of optics, gratings, detectors etc. Wkr, M. Herms.
Dear Colleague Martin Herms,
thank for this very benefit details & seem to be from your deep experience in this field.
my great regards
Raad
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