Question

With what is the solvent in an SEM specimen's cells usually replaced?

A) water
B) glycerol
C) a liquid transitional fluid, usually CO2, that has been vaporized under pressure
D) serum
E) hydrochloric acid

Answer 1

In SEM specimen preparation, cells are dehydrated using critical point drying with CO2, after which they are sputter-coated with metal.

Step-by-step explanation:

The solvent in an SEM specimen's cells is usually replaced with critical point drying using inert liquid carbon dioxide under pressure. This process is utilized to displace the water from the specimen, ensuring that the samples are dehydrated thoroughly, which is necessary for obtaining clear images in a Scanning Electron Microscopy (SEM) analysis.

After the critical point drying, specimens are sputter-coated with metal to prevent charging during electron beam analysis.

Answer 2

The solvent in an SEM specimen's cells is typically replaced with carbon dioxide through critical point drying, followed by sputter-coating to prevent electron beam charging.

Step-by-step explanation:

In the preparation of specimens for scanning electron microscopy (SEM), the solvent within a specimen's cells is usually replaced with a liquid transitional fluid, which is often carbon dioxide (CO2) that has been vaporized under pressure. This process is known as critical point drying and serves to displace water from the specimen without causing the surface tension effects that might otherwise distort or damage the sample's delicate structures. Post-dehydration, the samples are typically sputter-coated with a metal, such as palladium, to prevent charging by the SEM's electron beam during analysis.