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Standard Operating ProcedureHoriba/AIST-NT LabramTip-Enhanced Raman Spectroscopy (TERS)

ContentsStart-Up and preparation............................................................................................................................2

Physically.................................................................................................................................................2

In OMEGA................................................................................................................................................2

Focusing the laser on the tip apex...........................................................................................................3

Approaching the tip to the surface..........................................................................................................5

Topography image of the surface............................................................................................................6

Collecting a TERS Raman map.................................................................................................................6

Shut down procedure..................................................................................................................................8

About this document...................................................................................................................................9

Contact....................................................................................................................................................9

Horiba/AIST-NT Labram - TERS v1.0 9/15/2017

Start-Up and preparation

Physically1. Turn ON AFM controller box 2. Load sample onto sample stage3. Insert probe into tip holder4. Slide the tip holder platform in place and fix with top screw, connect laser cable.5. Open software: HORIBA LabSpec66. Open software: AIST-NT OMEGA.

In OMEGA7. Load the following scripts (select then press green arrow sign) in MACRO EXECUTOR (tab on the

panel on the right side of screen):a. head lightb. probe awayc. To contact.

Note: select phase to plot and Ex1 in case we introduce external signal, unselect square scans in case you want to acquire rectangular scans.

8. Click Video capture (Camera Icon ) window – top camera view is now active

9. Click on the Camera icon of the top camera window to enable side view camera.10. Physically: Focus on tip using the back top (x, y) and big bottom side (z) screws. NOTE: Only the

TOP view is focused (see picture).

11. OMEGA: Go to Tools (top bar) AC Mode. 12. OMEGA: Go to:

Find Tip (or Look around (Coarse tuning)). [ONLY TOP VIEW is shown]Adjust Photodiode.

13. OMEGA: Click on Initial Tuning: Resonance peak of the probe 130kHz (for standard silver TERS probes). For Ag probes, be careful to not select the second harmonic at 400kHz, reduce the frequency range up to 250kHz to select first harmonic. Set an amplitude of 12nm and length: 130um for Au probes/230um for Ag probes to start with.

14. Physically: Move side camera to UP position. [NOW, LATERAL VIEW is shown]Focus on the probe using back top (x,y) and big bottom (z) screws.


For the lateral view, probe should look like a snake tongue at the apex (to improve IMAGE contrast of the lateral view: Turn on head light and switch off the top view light).

15. In LabSpec: Select the lowest power (0.01%) and Turn ON the laser (turn on head light to see probe).

a. Position the laser on top of the apex of the probe (observe diffraction).

Click on Markers.

b. Position the green markers at the spot of maximum diffraction of laser with tip apex (Click in marker and select with the lateral arrow move)

Focusing the laser on the tip apex16. OMEGA: Go to Spec_Scan (Rainbow icon) Window:

a. Select XY objective (mode selector on the right side near icon).

b. Click on icon (view full available scan area)

c. Click on icon, move position in the map around and find the maximum diffraction peak (the camera view should show a clear laser diffraction).

d. Center the scan square window ( icon) at this point of max diffraction. (Important: The green marker of the camera window must be also centered in the diffraction at the probe position)

e. Cross check : In the rectangle area, move top and down, and left to right to observe how the light from the laser diffraction on the tip becomes weaker and also peak in LabSpec observed for 0.01% also becomes smaller.


17. OMEGA: switch off head light (HORIBA) and top camera light, remove side camera (Camera DOWN position).Physically: switch off room lights

18. LabSpec: Change laser power to 2.5% (1%, 10%, etc. depends on the sample that you will measure). Set the parameters as follows:

RTD:0.3sAcquisition: 0.3sAccumulation: 1sRange button: UnclickLaser mode: ManualEnable: EM Gain (100-150)AFM: ONSpectrometer position: e.g. 1600cm-1

You should observe similar signal:

Note: Ag probes: Signal is much lower and FLAT.

If you don’t get the signal expected: Go to OMEGA, Spec-scan and repeat steps until you observe a better signal like the one in the picture.


Only for Au probes (coated with Al)

19. OMEGA: In SCAN icon , Run a XY objective scan (pixels 18x24) with a size of 3umx4um.Check that the oscillation amplitude (Mag) is above 20000 (for Au probes).For broad photoluminescence peaks select Peak Area and select a broad range for peak area integration in the bottom right window

20. OMEGA: Select from and run a XZ objective scan (pixels 10x16) with a size of 2umx6um. Do the same steps as for XY objective scan, i.e. look for the maximum intensity value (Peak area) and move red rectangle icon to the center of the green cross.

21. You can run XY objective scan again to be sure you have good alignment of laser on the tip apex.

Approaching the tip to the surface

22. OMEGA: click “Auto” in AC mode control panel. The probe approaches to the sample and the amplitude graph should be then plotted.

23. OMEGA: Sweep Z (run): (Parameters: From 15nm to -1 or -2nm, points 250, 2,2, delay 30).a. Set Shift and NFx values to 30-50 and 180, respectively.b. Look at the set point value that you have and subtract it to the free amplitude value.

You will need HALF OF this value (usually around 1500 for Au probes and around 700 for Pt) in step 21.

Set point and gain are shown in the top panel: e.g. Sp 16683 Gain: 108 (This GAIN must be between 50 and 120, if below, click ADJUST GAIN button). Don’t modify this values, they are set automatically by the software

The Sp and gain are different to the Shift and Nfx values.

Optional: Click Fit phase button too.


24. OMEGA: In SCAN icon: Select Qscan (near icon), enable “error Z” feedback and select the data you obtained in step 20 (HALF VALUE of the difference between set point and free amplitude).

Topography image of the surface25. OMEGA: In select the area that you want to Scan: e.g. 7umx7um. Then, scan until you get a

nice picture.

For slope correction during scan click median fit line ( icon). If your sample is flat enough select subtract plane and click in windows underneath and select area.TO MOVE TO ANOTHER AREA:

i. First option without retracting: Click on and then move it to another place. Then start a new scan.

ii. Second option: If your desired location doesn’t fit the first option, go to and retract probe “-0.02 mm” (“minus 0.02 mm”) and then, move in X or Y direction. Then, click in AUTO to approach. Then start a new scan.

26. To stop scan before it is completed, the same “start new scan” button can be pressed. Partial scans are also saved.

Collecting a TERS Raman map27. Physically

a. Switch laser onb. Set desired power (typically 1-5%)


Z sweep GRAPH: See the set point minus free amplitude value (needed HALF OF THIS VALUE)

28. OMEGAa. Click Rainbow Icon (Spectrum scan)

b. Go to the area of interest with . Select the size of the area: usually 3umx3um or below for nice scan, 100x100pixels

c. Click next to “Spec-Top”, select the same nf shift and nf gain that you had in step

d. In , you have the option of select DUAL SPECT. When it is enabled, the software collects two maps: one of near field+far field (contact mode) and another one of only far field (few nanometers out of contact). This two images can be later subtracted to PLOT ONLY NEAR FIELD.

i. How to substract the contact minus out of contact:1. In the top BOX ICON, select Spectra2 (Far field: Raman contact mode)

image (usually opens automatically in a floating window): in select “A-B” and enable “Is B”.

2. Then, select Spectra1 (Far field + near field: tapping mode) image

(usually the Raman map in the background), in select “A-B” and then NOT enable “Is B”.

3. Now, after a map is acquired, click “Apply” in this window and the resulting signal should be ONLY the near field data. With the dual spect option you are sure that what you measure is really Raman.

e. Go to the top BOX ICON and open the topography file that you saved. It should be shown automatically in the bottom window (Height map).

f. LabRam: select the appropriate spectrometer position: e.g. for graphene set 1600 cm -1 g. Click on: “To contact”. The photoluminescence/Raman peak should be increased when

in contact with e.g. flake.h. Click again in “To contact” to non-contact. Now the photoluminescence/Raman peak

should be reduced.i. Keep doing this while moving the laser position in the XY objective scan to do final

adjustment of laser position on tip apex (when moving from contact to non-contact). Then, you should be ready for mapping.

j. Acquire a Raman map for the frequencies/peaks selected in the down right corner window (blue, red and green windows) that you want to plot:


Shut down procedure1. Turn off software2. remove tip3. turn off AFM controller box


About this document1.0 9/15/2017 Andrey Malkovskiy

Miguel Munoz-RojoInitial Document

We encourage everyone to contribute to this document. Please follow these steps to integrate your comments/additions/suggestions:

Save this file to your computer Turn on the “track-changes” feature in Word Make your comments/additions/suggestions and save the file Email the finished document to the contact indicated

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