Flashcards
Nanosurfaces & Characterisation
Cards in this deck (14)
- 1Name 4 key factors that make nano surfaces and internal interfaces important1) Surface/Internal Energy
2) SA:V Ratios
3) Self-Assembly (Static Structure)
4) Self-Organisation (Dynamic Structure) - 2Explain the relevance of surface area to volume ratiosSA:V varies with r, therefore highly impacted by the nanoscale
More contact with surfaces and interfaces when size decreases - 3Explain the concept of surface energySurface energy is the energy required to break up the original crystal structure when forming new surfaces
- 4What is internal interfacial energy a function of?NP curvature
- 5What is the SA:V ratio a function of?Radius
- 6What techniques could be used to quantify size and morphology of nanoparticles?Microscopy (Mainly electron)
SEM/TEM - 7Explain the concept of SEM ImagerySample irradiated with e-
Results in the reflection of electrons back to a detector
1) SE from surface 2) BSE from deeper down - 8What causes SEM contrast in BSE mode?Atomic Number (Ar)
- 9What causes TEM contrast and why?Density
TEM involves the transmission of electrons through a sample - 10How is structure characterised in NPs?Diffraction
X-Ray (XRD) or Electron - 11How can XRD be used to quantify the structure of NPs?An XRD graph is produced with peaks corresponding as such:
IDENTITY = Peak Location
CRYSTAL SIZE Peak Width - 12Name 3 factors that can influence the peak broadening in XRD1) Instrumental Broadening
2) Crystallite Size Broadening
3) Lattice Strain Broadening - 13Name 3 spectroscopic techniques for characterising chemical composition1) XPS
2) UV-Vis
3) Photon Correlation Spectroscopy - 14Explain how XPS is used to quantify chemical compositionIrradiation of sample with x-rays releases photoelectrons
Production of peak-wise graph
IDENTITY = Peak Location
HEIGHT = No. of surface atoms
Ion bombardment allows for deeper analysis