The diamond is an E color, vvs1, 1.15 carat with moderately strong blue fluorescence.
The Raman spectrum is shown below. Absolutely no emissions except for the characteristic diamond line at 1332 per centimeter. When the applications rep put the cursor on the spike and said it was 1332 I remembered that that was an important diamond signal. Maybe Dr. Alzheimer hasn't caught me yet.
Although the Raman spectrum is measured in wavenumbers like the IR it is a very different critter.It is light SHIFTED from the exciting wavelength. A laser beam is shined on whatever the specimen is and it makes the molecules shake rattle and roll and they re emit some of the energy. It is similar to fluorescence but about 100 times weaker so much harder to detect. And if the specimen does fluoresce it makes the Raman signal harder to get. So they offer different wavelength lasers in hopes of not stimulating fluorescence. The usual lasers are 785 nanometers, (a solid state InfraRed laser) 633 nanometers (Helium Neon line but now sometimes done with fancy solid state lasers anyway.) or 532 nanometers (Diode pumped solid state green) Sometimes they offer a YAG laser at 1064 nanometers and other lasers are used as well.
The Raman shift always looks the same regardless of the excitation wavelength. It is shifted by characteristic numbers of waves.
Notice that the Y axis is labeled in counts. That is how many Raman photons are emitted. By contrast, the FTIR is an absorbance value just like in UV-VIS.
Monday the guys from Renishaw are bringingtheir Raman unit. Some of the PIs are going to be out of town so I will get to play more. (I think
)
