David Millard
FTIR/RAMAN/IR Microscope
Purpose:
The goal of this lab was to determine the composition of an unknown liquid solution using the
FTIR as well as using the IR microscope to determine the composition and match an unknown
fabric to a known sample.
Introduction:
The FTIR uses an infrared laser to detect the different bonds and functional groups that are
present in the sample you introduce into the instrument. The samples have to be liquid in order
for the laser to properly detect the compound. The RAMAN detects the scattering of
radioactivity in the compound. The Microscope allows the user to find the composition and
bonds that is able to be used in the FTIR only with solids such as fibers from clothing.
Procedure:
FTIR
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Insert the correct loading tray and sample holder into the instrument.
Open Resolution Pro on the computer
Click on “center burst” near the bottom of the page.
o Make sure the black handle on the right side of the FTIR is pushed down.
o Make sure the center burst number is ranging between 1.2 and 5.
o Check parameters: view – interferrogram, aperture – 2cm-1 at 2000cm-1,
Sensitivity – 1, click ok.
A scan dialog box should appear.
o Check parameters in electronics tab:
 Speed – 20 KHz, Filter – 5, UDR – 2, Resolution – 0.5, Sensitivity – 1,
Scans to add – 16, Save range 4000-7000 cm-1.
Check the parameters in the optics tab:
o IR source – Mid IR, Beam – internal, detector – DTGS DET #1, Beam splitter –
KBR Broadband, Accessory – None, Source – 2cm-1 at 2000cm-1, Microscope –
box, detector – left, optics mode – reflectance.
Click background.
Save background.
Name background.
Go to collect tab at top of the window.
o Select rapid scan.
o Check to make sure the electronics and optics parameters are the save as above.
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Go to background tab.
o Make sure the background properties box says: Status = Exits and there is
information about the background showing.
o If no background exists, define one.
 Exiting background – hit select.
 Use current.
 Open Collect background after sample.
Computations tab.
o Make sure these options are what are being shown:
 Compute, Ratio, Truncate, Stop (in red), absorbance to percent
transmittance (in grey).
o If the options do not show up in this order hit “set to default.”
Hit scan
Name standard
o Take a screen shot of your background and polystyrene.
 “print screen”
 Open “paint” and paste picture in paint.
 Save image to desktop and put on flash drive or print out.
 Repeat same steps for polystyrene
o Go back to graph in resolutions pro program.
 Select polystyrene sample graph and change the absorbance to
“%transmittance” by selecting “% transmittance” under the tab at the top
of the window.
When finished, close out of the program, and remove the sample holder and loading tray,
but leave the instrument and computer on.
IR Microscope
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Make sure the instrument is on and in bypass mode.
Fill dewer with liquid nitrogen.
Insert the funnel into the top of the microscope and fill until liquid nitrogen flows out the
notch on the side.
Wait 20 minutes to run any samples.
Open Varian Resolution Pro, Collect>Rapid scan>computations.
o Under computations tab
 Check to make sure these options show up:
 Compute, Ratio, Truncate, Stop (in red), absorbance to %
transmittance.
Optics tab – Set accessory to none.
Place ATR crystal from white box onto the microscopes barrel.
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o Make sure the notches are on the left
 Slide in until you hear two clicks.
o Place the gold slide from the white box under the barrel on the stage.
o Make sure that the cracks are not located under the crystal.
Take a background scan.
o Background button
o Collect>rapid scan>setup
o Change the view from interferogram to processed
Place a known fabric sample onto the gold plate so it lines up with the crystal.
o Slowly raise the stage using the fine adjustment knowb until the lines on the
computer screen can no longer be sceen on the computer screen or until resistance
is met against the crystal.
o Make sure the known fabric sample and crystal touch completely.
o Click the four way arrow to bring the screen back.
o Hit scan.
After the scan, access the library by going to operations>Varian search>search.
o Spectra tab (or first tab) and search
o Record the results that match your spectra graph
o Click on its spectra graph to highlight it and it should bring up another spectra to
compare.
When finished, leave computer and instrument on.
RAMAN
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Fill RAMAN (blue dewer) with liquid nitrogen and wait twenty minutes.
Make sure the instrument is on.
Top off the dewer with liquid nitrogen after ten minutes.
Turn on the power supply to the laser located on the floor (press switch and turn key).
The two levers on either side of the RAMAN must be switched to on.
The lever inside the RAMAN should be up with the bypassed closed.
Prepare a sample and put a solid capillary tube in to a depth of one inch.
Liquids are placed a four inch NMR tube.
TO find red/pink dot, lower lid halfway and adjust x, y, z knobs to center the laser.
Open Varian Resolution Pro.
From current scan menu select raman scan.
o IR source – off, beam – right, detector – raman, beam splitter – quartz near IR,
ATR crystal – none, optical filter – holographic notch, aperture – open.
Select laser tab, click to turn on diode.
Press shutter switch in from of RAMAN.
Set power to highest of all three.
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Return to software and the laser tab and adjust the value of laser control current to 600700mQ.
Setup, center burst should appear. Click auto scale icon and use the x, y, and z knobs
until the burst peak is max.
Click scan.
Shutting down.
o Turn off laser by selecting RAMAN scan and laser tab, slick “turn off diode”.
o Press shutter button on front of RAMAN to close the shutter.
o Remove the sample.
o Turn off laser (turn off key and turn off switch).
o DO NOT turn off computer, FTIR or RAMAN accessory.
Different percent compositions of 2-butanone were run through the FTIR to determine the
components of the unknown sample.
Unknown
2-butanone
2-propanol
20% 2-butanone
40% 2-butanone
60% 2-butanone
From the scans that were run, we determined that the mixture of the unknown was closest to the
80% 2-butanone, and with the way that the IR’s flowed with the higher the percentage of
butanone, we believe that the unknown was a 90% 2-butanone 10% 2-propanol solution.
The unknown picked for the IR microscope was Unknown C, which was a black fabric with a
composed of a stretchy material. The IR of the fabrics tested are as followed:
Unknown
50% cotton 50% polyester
80% cotton20% polyester
82% polyester 18% clasty
85% nylon 15% elastic
95% cotton 5% spandex
With the samples we ran, I believe that our unknown was 100% polyester.
100% polyester
Conclusion:
We were not able to run anything with the RAMAN due to the laser not functioning properly.
The Microscope was interesting to use, but there was an issue with how much pressure you
needed to have on the crystal with the fabric to obtain a good IR. I believe that we had a suitable
amount of pressure to get IR’s that were satisfactory, but we were nervous that we would crack
the plate. The FTIR was somewhat interesting. When setting up the parameters, we had trouble
setting up the proper center burst. Also, we used solutions that were already premade but found
out that we were supposed to create our own solutions to test against the unknown. With the
premade solutions, we were still able to find a somewhat close match with what the unknown
could possibly be.