Images Flashcards
In this SEM image, why do some areas appear brighter than others?
Orientation effect - electrons preferably escape in directions normal to the surface. The bright areas of this image are those in the same direction as the detector’s orientation.
In this optical microscope image, why does the center appear brighter than the edges?
The intensity of the light is generally brighter in the center.
The SEM image captured here seems very blurry. What might have caused this?
Astigmatism - an off-axis aberration.
The following SEM image appears to have horizontal lines running across it. Where might this come from and what could we do to resolve it?
It comes from vibrations intrinsic to the building/environment. Can perform SEM in basement or on vibration isolation table or use frame averaging software.
We cannot quite resolve the small pillars in the image. What is the problem and what parameter could we change on our SEM to correct it?
The depth of field is to narrow. We could decrease the size of the aperture or increase the working distance.
Fine contrasts can be seen on the SEM image on the right that are not visible in the image on the left. What effect might be influencing this and how could we correct it?
Charging. We could reduce it by reducing the acceleration voltage.
The lower SEM image appears much sharper than the one above, but is less smooth in appearance. What parameter was likely changed and how would that result in a less smooth appearance?
The lower image was taken with smaller probe current. This leads to lost signal to noise ratio (SNR).
The following SEM image appears extreemly bright and unresolved. What might cause this and how might we correct it?
Charging. Can lower acceleration voltage or probe current or coat with conductive material.
These are images of a biological sample taken with an SEM. How were the two samples prepared?
Sample on left seems to have been air dried because the cells are collapsed due to liquid/gas boundary. Sample on right was likely prepared with a crtical point drying method like rapid freezing to avoid water/vapour boundary (image).
The following image was captured with an SEM. What is the likely cause of the dark region and how can we avoid it?
Carbon contamination due to high energy beam decomposing hydrocarbons. Can decrease magnification or mose to different area.
Many lines appear in the TEM image of silicon below. What are they?
Kikuchi lines.
The following structures were found in a TEM image. What are they and what causes them?
These are wedge fringes fromed by continuous thickness variation since transmitted beam intensity is oscillating function of speciment thickness.
The following TEM artifact was discovered upon inspection of the image. What are the lines and how do they arise?
These are bending contours that appear when Bragg condition is satisfied. Tilt sample and they will move, if not they could be wedge fringes.
The following image was captured with an AFM. What might cause the duplicate images and what could we do to correct it?
Double/multiple broken tip causes multiple images. Must replace the tip.
The following AFM image seems to be very blurry and has various spots/inconsistancies. What might cause such an image?
Looks like sample surface has contaminated the tip so something sticky is on end of tip and it is causing inconsistant tip shape.
The following image was captured with an AFM. Why is the center brighter and how can we correct it?
Center is brighter because of the non-linear swinging of the cantiliver tube looks like we need a third order bow correction in software.
Label the XPS spectrum.
