Post subject: Raman Spectrum of my Missus' engagement ring
Posted: Sun May 09, 2010 12:37 am
Platinum Member
Joined: Tue Jan 02, 2007 8:20 pm Posts: 2659
I only got one shot at the Raman microscope.This one. We put Leggsie's engagement ring under the 20x objective and fired the various lasers at it.
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 )
Last edited by G4Lab on Mon May 10, 2010 9:32 am, edited 1 time in total.
Post subject: Re: Raman Spectrum of my Missus' engagement ring
Posted: Tue Jun 05, 2012 4:20 pm
Established Member
Joined: Sat Jun 02, 2012 12:50 am Posts: 11 Location: Colombo, Sri Lanka
"The Raman spectrum is shown below. Absolutely no emissions except for the characteristic diamond line at 1332 per centimeter." It's reciprocal centimeter, or cm-1, if I may say, wich makes a big difference. Take it easy! Eric
Post subject: Re: Raman Spectrum of my Missus' engagement ring
Posted: Mon Jun 11, 2012 4:10 pm
Platinum Member
Joined: Tue Jan 02, 2007 8:20 pm Posts: 2659
Quote:
"The Raman spectrum is shown below. Absolutely no emissions except for the characteristic diamond line at 1332 per centimeter." It's reciprocal centimeter, or cm-1, if I may say, wich makes a big difference. Take it easy! Eric
I think you might need to go back, and review your junior high school arithmetic. "Wavenumbers per centimeter" is exactly the same as reciprocal centimeters. Which, if I may say, makes no difference, whatsoever.
Dr. Brian! Dr.Bill!
BTW, we bought the one at the beginning of this thread. Bruker Senterra.
Post subject: Re: Raman Spectrum of my Missus' engagement ring
Posted: Mon Jun 11, 2012 8:45 pm
Active Member
Joined: Wed Aug 02, 2006 1:10 pm Posts: 53 Location: Louisville, KY
EthicalGems wrote:
"The Raman spectrum is shown below. Absolutely no emissions except for the characteristic diamond line at 1332 per centimeter." It's reciprocal centimeter, or cm-1, if I may say, wich makes a big difference. Take it easy! Eric
Hello: "1332 PER cm" is the SAME as "1332 cm-1"
_________________ Marty Haske
SAS2000 Spectrophotometer Analysis System
Adamas Gem Lab
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