Scanning electron microscopy (SEM) is an electron microscopy technique in which a tiny beam of electrons is scanned across the surface of a sample. A high-resolution 3D image of the sample surface is generated when the electron beam strikes a metal-coated specimen and the electrons reflected (back-scattered) or given-off (secondary electrons) are detected.
Equipment:
Hitachi S4700 SEM (Ultrahigh resolution SEM with field-emission gun)
Hitachi S2600 SEM (Environmental/low vacuum variable pressure SEM)
Tousimis Critical Point Dryer and Cressington Sputter Coater to prepare samples for Hitachi S4700 SEM
Sample Preparation:
Hitachi S2600 – samples are not required to be dehydrated and coated
Hitachi S4700 – samples are required to be dehydrated and coated
- Fixation
- Dehydration
- Critical point dry (complete dehydration)
- Mounting
- Sputter coating (with Gold and/or Platinum)
- SEM
Comparison of S4700 and S2600
| Hitachi S4700 Field emission (FE)-SEM | Hitachi S2600 Variable pressure (VP)-SEM | |
| Resolution | Ultrahigh up to 2 nm | Relatively high up to 5 nm |
| Electron Gun | Field emission cold gun - very bright, tiny spot size, low voltage | Tungsten thermionic gun - less accurate beam spot |
| Vacuum | Ultrahigh | Low, variable setting (1 – 270 Pa) |
| Sample Condition | Dry, coated with metal | Wet sample can be viewed No sample preparation is needed |
Publications:
Šola, K., Gilchrist, EJ, Ropartz, D., Wang, L., Feussner, I., Mansfield, SD., Ralet, M-C. and Haughn, GW. (2019). RUBY, a Putative Galactose Oxidase, Influences Pectin Properties and Promotes Cell-To-Cell Adhesion in the Seed Coat Epidermis of Arabidopsis, The Plant Cell, 31(4):809-831.
Martone, PT., Janot, K., Fujita, M., Wasteneys, GO., Ruel, K., Joseleau, J-P. and Estevez, JM. (2019). Cellulose-rich secondary walls in wave-swept red macroalgae fortify flexible tissues. Planta 250, 1867–1879.
Tran, A., Hamad, WY. and MacLachlan, MJ. (2018). Fabrication of cellulose nanocrystal films through differential evaporation for patterned coatings. ACS Applied Nano Materials 1 (7): 3098-3104.
Wang, PX., Hamad, WY. and MacLachlan, MJ. (2018). Size-selective exclusion effects of liquid crystalline tactoids on nanoparticles: A separation method. Angew Chem Int Wd Engl. 57 (13): 3360-3365.