Introduction to STM Image Processing II

Notice I:
All, or any part of the following material may be downloaded and used for personal or educational purposes as far as

there is a clear indication of the © author DcsabaS ^TM, with a link to this www site.
Notice II:
All the images presented in the following were made by using the "STM for Students"^TM developed by DÓRA, Gyula.

---

by DARÓCZI, Csaba Sándor
motto:

Make everything important more visible !

but hide the others!

Optical Grating III ( 1000 nm × 1000 nm, covered by Gold ) For starting point we choose the image that we got under the section "Tilted Image". Near to the center of the image there can be seen a relatively bright area that corresponds to a somewhat higher region of the sample. The question is, how much higher, and actually how big is that higher region? Unfortunately, the present image of the measured data is a little big misleading. The height of the given object is not so large as it seems to be...

Volume The light shaded image makes a more realistic impression in this respect, but now we need something more. Therefore several line cuts have also been made, that can be seen in the next 4 images:

Measuring After studying the previous line cuts, we can make a rough estimation of the dimensions of the investigated object. We can try to estimate at once the dimensions, or just to give upper and lower limits. Here are my estimations:

Min. Height:	2 nm	2 nm	2 nm	3 nm
Mean Height:	3 nm	2.5 nm	2.5 nm	4 nm
Max. Height:	5 nm	4 nm	3 nm	6 nm
Min. Width/Length:	350 nm	400 nm	800 nm	700 nm
Mean Width/Length:	400 nm	450 nm	850 nm	800 nm
Max. Width/Length:	550 nm	550 nm	900 nm	900 nm

Now we can calculate the volumes:

Min. Volume:	(2+2+2+3)/4 nm × (350+400)/2 nm × (800+700)/2 nm =	0.633 × 106 nm3
Mean Volume:	(3+2.5+2.5+4)/4 nm × (400+450)/2 nm × (800+850)/2 nm =	1.05 × 106 nm3
Max. Volume:	(5+4+3+6)/4 nm × (550+550)/2 nm × (900+900)/2 nm =	2.23 × 106 nm3

The obtained volumes correspond to that of the largest viruses. (NOT computer viruses!) Although we can not be sure, of course, that it was a virus, it is generally true, that in common circumstances (in the open air) any surface can be contaminated very easily with materials of organic origin.

3D Grating ( 2500 nm × 2500 nm, covered by Gold ) If an image is not very noisy, it can look greate in 3D representation. In this case, for example, no previous image proccessing had been applied to the image, because the initial signal/noise ratio is about 5! (See the line cut !)

3D Nickel ( 200 nm × 200 nm, sputtered Nickel ) This landscape like image was taken from a Nickel sample sputtered onto a Si substrate. For perfect impression of a real 3D scene we have also applied light shading technique.

Color ( 2500 nm × 2500 nm, covered by Gold ) We can apply a color palette to a given image. In this case, for example, a palette that is similar to the black body radiation spectrum was applied. Fortunately, - in this case - even the black-and-white printing of the image would not result erroneous gray scale.

Color II ( 2500 nm × 2500 nm, covered by Gold ) It is possible to use more colors in the palette which often leads to amusing appearance. Now the black-and-white printed image would mislead one about the height of the different spots of the sample.

Crater on HOPG ( 80 nm × 80 nm, HOPG Graphite by DcsabaS) With a short voltage pulse (10 s, 100 V) a little crater was generated on HOPG Graphite. Fortunately, the scanning tip had not been damaged very much and several scans after the puls could also be done. Here we can see the crater itself and a "big" terrace on the left side of the image.

Line Offseted HOPG This surface is not very easy to scan because it has spots with rather different height. What is more, the very end of the tip became instable which resulted the horizontal stripes in the previous image. The stripes could be removed by using height offset on every individual horizontal lines.

Craters The height offset method was applied to every horizontal line of these images. The scanned regions were 160 nm × 160 nm, 80 nm × 80 nm and 20 nm × 20 nm, respectively. We can clearly see that the crater is actually a doublet.

Line Cut through Craters We have made a line cut through the terrace and the craters. The depth of the smaller crater can be estimated as 0.3 nm, that corresponds to 1 damaged layer of the HOPG sample. The other crater is at least 2 layer deep, however we can not tell it exactly, because the A/D converter was overloaded.

Stereo Image of Ni ( 200 nm × 200 nm ) Choose Your 14" monitor resolution and adjust the red line's length to 6.5 cm. Than try to look far away, while focusing at the images. For better result You can separate the two images with a sheet of paper. Available resolutions: 640 × 480, 800 × 600, 1024 × 768, 1280 × 1024.

Stereo Image of Cr ( 500 nm × 500 nm ) Choose Your 14" monitor resolution and adjust the red line's length to 6.5 cm. Than try to look far away, while focusing at the images. For better result You can separate the two images with a sheet of paper. Available resolutions: 640 × 480, 800 × 600, 1024 × 768, 1280 × 1024.

E-mail

#

Last Mod: Fri, 12 Oct 2001 07:40:50 GMT