Additional Info Flashcards
What reflections are absent from the simple lattice structure XRD pattern?
None
What reflections are absent from the body centered lattice structure XRD pattern?
(h+k+l) is odd
What reflections are absent from the face centered lattice structure XRD pattern?
h, k, and l are mixed, odd and even
What reflections are absent from the diamond lattice structure XRD pattern?
h, k, and l are mixed; or (h+k+l)=4n+2
What is the expression of Bragg condition?
Name the seven crystal structures.
Cubic, tetragonal, orthorhombic, rhombohedral, monoclinic, triclinic, hexagonal
Name the four types of lattice structures.
Simple, base-centered, body-centered, and face-centered.
What is the resolution of an optical microscope?
200 nm
What is the formula for the resolution of an optical microscope?
(0.61*lambda)/NA
What is the formula for the depth of field of an optical microscope?
(2R) / [tan(alpha)]
What is the resolution of a TEM?
0.1 nm
What is the resolution of a SEM?
1 nm
What are the lateral and vertical resolutions of a STM?
Lateral: 0.1 nm
Vertical: 0.01 nm
What are the lateral and vertical resolutions of a AFM?
Lateral: 1 nm
Vertical: 0.1 nm
What is the formula for oscilation frequency?
What is the formula for reduced mass?
What are the types of vibrations that contribute to a 3 atom molecules’ 9 degrees of freedom (specify the number of degrees of each type).
Symmetric Stretching (x 1)
Asymmetric Stretching (x 1)
Bending (x 1)
Translational (x 3)
Rotational (x 3)
Which vibration[s] type[s] of the following molecule will be visible on an IR spectrum?
Asymmetric stretching
Bending
Which type[s] of vibration[s] will be visible on a Raman spetrum of the following molecule?
Symmetric stretching
Which type[s] of vibration[s] will be visible on a Raman spetrum of the following molecule?
Symmetric Stretching
Asymmetric Stretching
Bending
Which vibration[s] are visible on the IR spectrum of the following molecule?
Symmetric Stretching
Asymmetric Stretching
Bending
Identify the unit cell of the honeycomb lattice (small dots) and the rectangular lattice (big dots). And what are the unit vector lengths of the two types of unit cells?
Honeycomb is hexagonal unit cell with edge length √3 angstroms.
Rectangular cell has edge lengths 2√3 and 3 angstroms
What is the typical energy and wavelength of visible light in an optical microscope?
Energy: ~ 2 eV
Wavelength: ~ 600 nm
What is the typical energy and wavelength of electrons in a SEM?
Energy: ~ 10 keV
Wavelength: ~ 0.1 angstom
What is the typical energy and wavelength of photons used in x-ray diffraction?
Energy: ~ 10 keV
Wavelength: ~ 1 angstrom
Which energy level makes copper a good conductor?
4s (this is the conduction electron)
In x-ray terminology, what are the names for the x-ray line #1, #2, and #3 (see marked)?
line #1: Kα2
line #2: Kα1
line #3: Kβ
The 2p atomic shell has two energy levels, what causes such a splitting?
spin-orbit splitting (or l-s, l+s)
What is the ratio of electron population between the higher energy level (#4) and the lower one (#5), and why?
2:1
The l+s=3/2 level has 4 states, the l-s=1/2 level has 2 states.
What is the function of a Gobel mirror, how is it able to achieve both beam monochromation and collimation?
It focuses x-ray by following contour of parabola and place the source at focal point (collimation), and the way it reflects x-ray is through Bragg diffraction (strict wavelength correlation leads to monochromation).
What are the five lenses usually called in this system? Name them sequentially from the top down.
2 x condenser lens
objective lens
2 x projector lens
Which of these two configurations is the diffraction mode?
Left
How is selected area diffraction (SAD) performed with a TEM?
In imaging mode, use selected area aperture to select region of interest. Switch back to diffraction mode.
Two aperture positions are marked 1&2, what are their corresponding apertures named? Which can be used to enhance mass density contrast and why?
1 - objective aperture
2 - selected area aperture
Objective aperture used to enhance mass density contrast because it can block scattered beams from denser regions, thus enhancing contrast.
Explain the formation of Kikuchi lines.
Defects scatter beams which then go through Bragg diffraction on two sides, leading to a pair of lines.
Explain the formation of bending contours.
On a curved surface, Bragg diffraction can be met on two locations and they distort beams away leading to a pair of dark lines on the image.
How do we distinguish mass density contrast from diffraction contrast under TEM?
Tilt the sample (diffraction contrast changes dramatically with angle while mass density does not).
Draw the (20¯23) atomic plane.
What is a hydrogen bond and why is it unique to hydrogen?
When hydrogen atom partially loses its electron it becomes extremley small and can very closely approach other positive ions and form a bond with Coulomb forces. It is unique to hydrogen because of its smallness.
What is the difference between a “textured” and “epitaxial” film?
Epitaxial means ordered in all 3 directions, textured means ordered only in the out-of-plane direction.
