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22 Cards in this Set
- Front
- Back
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What does LEED stand for? What does RHEED stand for? |
Low Energy Electron Diffraction. reflection high energy electron diffraction. |
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If I have 2 types of atoms on the surface, are Primitive and Cubic degenerate? |
No |
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How do we determine the sizing of the unit cell of the surface? |
Relative size in each axis to the unit cell of the bulk material |
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What is surface relaxation? |
Surface layer gets closed to bulk substrate |
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What is reconstruction? |
Atoms reposition to maximize bonding |
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In the LEED pattern is the surface cell larger or smaller than the unit cell? |
Smaller |
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What is the optimal incident angle of LEED? |
0 |
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How do we prevent secondary electrons from impacting our screen in LEED |
Electron filter is negatively biased |
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What is the angle difference from real space to reciprocal space? |
90 degrees |
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How does diffraction differ for surface cell in reciprocal space? |
The reciprocal space are rods |
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Are the spots brighter or darker spots? |
Darker |
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Why can we use a high energy for RHEED. |
Large incident angle glances the surface. |
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What method is related to RHEED, but with X-rays |
GID (Grazing Incidence Diffraction |
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What shape are families of Miller Indices in RHEED pattern? |
Circles |
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Why do we block the centre spot in LEED and RHEED |
too bright |
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RHEED oscillation allows us to monitor |
Real time growth and quality of surface layers |
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If our angle is not perfect in LEED then how will the peaks shift |
The peaks will shift to higher angles. |
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LEED and RHEED are the only surface sensitive __________ techniques |
Real Time |
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What does low intensity correspond to RHEED oscillation? |
rough surfaces |
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Why do we need UHV for RHEED and LEED |
These techniques are surface sensitive and exposure to air will change the surface |
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Does RHEED produces more diffraction points than LEED or less? |
More |
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Why do lines appear on RHEED patterns? |
Kikuchi Lines |
