Characterization Methods and Case Studies on Characterization Strategies Flashcards
Within nanochemistry, what type of information can be extracted using a SEM, which modes (detectors/techniques) can you typically apply?
High-energy electrons are used to obtain a contour profile of the surface
Within nanochemistry, what type of information can be extracted using a TEM, which modes (detectors/techniques) can you typically apply?
nhkdfsl
Explain situations that make powder X-ray diffraction as a strong technique within nanochemistry.
jfksl Scherrer equation(!)
What is the principles behind XPS, and when does it become useful? What is state-of-the-art with respect to total pressure over the sample when collecting XPS-data?
Generates photoelectrons (only) from the surface of the sample (2-3 nm).
Empirical formula, chemical state, electronic state can be found –> what elements are bonded to what.
Super-low pressure (ultra-high vacuum)
Consider a protein. Discuss which type of information you may derive on structure and properties by using methods like FTIR, XRD, TEM, XANES.
fds
Give some examples showing the importance of performing operando studies rather than just ex-situ investigations. Say you do such a study (at a synchotron) on (i) bimetallic catalyst on a mesoporous oxide support; (ii) on a cathode (or anode) electrode of a Li-ion (Na-ion) battery; which type of data will you collect and analyze, and why?
fjklsd
Give examples of how nanomaterials are implemented in a Li-ion battery. Discuss and list examples on other methodologies for sustainable energy conversion, storage and use, where nanomaterials are essentials.
fdsjklfjsl
Explain why powder XRD provides an average picture while TEM provides information for just a selection of very few situations/particles.
- XRD collects info from the entire sample (add up?)
- TEM only study a smaller area of the surface at a time
How could these methods best be used in your science where you synthesize and study a nanoparticle based catalyst for a specific process?
fjdkslfjsdlk
How can XRD be used to distinguished between a solid solution, a sitation with segregation into two non-miscible phases, and a situation with a core-shell structure of targeted A-B bimetallic NPs?
fdjsklfs
Describe an experiment where you can study the oxidation state of the A-B elements of the NPs upon treatment of the materials at different temperature - atmosphere conditions.
fjdsklfjl
How can you determine the crystallite size of a CdSe NP?
fjksdlfj
Imagine that you were collecting powder X-ray diffraction data for a stack of GO layer (i.e. a GO material/powder). Actually, you did a continuous chemical conversion of GO to RGO, took out a sample at various intervals, and measured XRD. How will the diffraction pattern change during the conversion process, from GO to RGO? Make a sketch u bitch
RGO has smaller distance between layers –> diff. pattern will shift to the large 2theta values.
(graphene oxide has repulsive functional groups >:( )
Imagine that you did a similar experiment on a graphite electrode material as anode for a Li-ion battery, during electrochemical cycling. How will the XRD pattern change on lithiation of the graphite material? Make a sketch
fdsjkl
If your sample contained metalorganic molecules, deposited as a weakly polymerized film on the surface of a substrate, how will you go ahead to detemine the oxidation state of the metal atom, and to explore which functional groups remain in the sample after the deposition process? Do you expect TEM and XRD to be useful methods for some characterization aspects of your sample?
fdjsklf
