Nanotechnology: A Maker's Course Week 4

True/False: The MicroCT is similar to a hospital CT or CAT scan in that the machine wraps around a stationary stage where the subject is sitting/laying?

False

The X-rays used in XPS are at ______ energy.

High

In darkfield imaging, only light that is _________ collected by the objective. (select the best answer)

Scattered

What can XPS tell us about a sample? Select all that apply

The elements present on the surface

Why might the spectrum of particles, like nanorods, that are long and thin have two peaks compared to that of round particles, which have one peak? (Select the best answer)

The long and thin particles have two dimensions that scatter ligth at different wevelengths

On the y-axis of an XPS plot is "Intensity". What does this axis represent?

The number of electrons leaving the sample

On the x-axis of an XPS plot is binding energy. What does this axis represent?

(Not The amount of energy necessary to break bonds in a molecule; The amount of energy needed to bind two atoms together)

XPS can be used to analyze the top ____ of a sample.

10 nm

Which of the following can be done with the final z-stack of images produced by the MicroCT?

All of the above

During XPS, when a high-energy X-ray hits atoms on a sample surface, what does it do that ultimately leads to data collection?

Displaces atoms' electrons

Any specimen smaller than an adult human can fit and be scanned with a MicroCT?

False

When prepping a sample for the MicroCT you often have to damage it in some way to get the best possible image.

False

Electrons closer to an atom's nucleus typically have ______ binding energies than electrons farther away from the nucleus.

Higher

Which of the following can happen to light when it hits matter? (Select all that apply)

It will be reflected It will be absorbed

Which of the following can happen to light when it hits matter? (Select all that apply)

It will be transmitted It will be absorbed

Because x-rays can be potentially dangerous the whole MicroCT is lined with what material?

Lead

In order to stabilize a sample for scanning it may be necessary to wrap it up before placing it on the stage. What would be the best material to package a sample in before running the MicroCT?

Light plastic bottle filled with cotton

Electrons farther away from an atom's nucleus typically have ______ binding energies than electrons closer to the nucleus.

Lower

Why might taking a scattering spectrum of nanoparticles take longer than taking a spectra of a bulk material?

Nanoparticles are small and scatter less light

What order do the x-rays pass through the MicroCT?

Target, stage, detector

In darkfield imaging, why do the particles of different sizes appear to be different colors? (Select the best answer)

The particles scatter different wavelengths of light

What happens when x-rays hit a very dense part of the sample?

They are stooped ar absorbed by it

When preparing samples for optical spectroscopy why is the silicon surface coated with polylysine?

To prevent nanoprarticles aggregation

Why are tweezers used during XPS sample preparation? (Select the best answer)

To prevent sample contamination

Why are tweezers used during XPS sample preparation? Select the best answer.

To prevent sample contamination

As the nanoparticle size changes, the peaks in the scattering spectra shift to different wavelengths.

True

The way light scatters or reflects depends on the size of an object

True

True/False: In XPS, the binding energies for various elements are known, which enables a user to match peaks in an XPS plot with specific elements.

True

True/False: The size of the data produced by the MicroCT is quite large. Files can often take up 20-30GB of space.

True

True/False: When prepping a sample it is best to remove it from any liquids and reduce the amount of dense objects in or around the sample. 1 / 1 point

True

The cross-sectional stack of images produced after the CT scan is processed is called the:

Z-stack

Electrons in a neutral/uncharged atom typically have _____ binding energies than electrons in an atom with a 4+ oxidation state.

lower

Using XPS you can obtain information about the chemistry of your sample's ______.

surface

When preparing samples for optical spectroscopy why is the silicon surface coated with polylysine?

to help nanoparticles stick to the silicone surface

What type of information does XPS give about the surface of a sample?

Chemistry

In XPS, what information can be used to identify elements on the surface?

Electron binding energy