Final answer:
TEM uses a transmission method to create highly detailed 2D projections of thin samples, offering higher magnification and resolution, while SEM scans the surface of samples, producing 3D images with lower resolution compared to TEM.
Step-by-step explanation:
The image formation in a transmission electron microscope (TEM) and a scanning electron microscope (SEM) differs in several ways. Firstly, the TEM creates a 2D Projection by using electrons that pass through a thin sample, allowing it to resolve details as small as 0.1 nm and providing magnifications of up to 100 million times. This method reveals internal structures like organelles and the interior of membranes. On the other hand, the SEM forms a 3D Surface Imaging by using secondary electrons emitted from the primary beam interacting with the specimen's surface, typically magnifying up to 100,000 times with a resolution between 3.0-20.0 nm, which is less detailed than TEM.
The TEM utilizes Bright-Field Imaging, where the electron beam is transmitted through the specimen onto a detector, producing an image. In contrast, the SEM's Dark-Field Imaging involves scanning the sample's surface in the x and y directions, with a CCD detector processing the data for each electron position to generate detailed images of surfaces.
Essentially, the TEM operates on Transmission of Electron Flow, where the electrons pass through the specimen, while the SEM relies on Scanning Electron Flow, scanning the surface of the specimen instead of transmitting through it. The core difference in their functionality is that TEM requires specimens to be thin and examined in a vacuum, suitable for detailed internal examination, while SEM can view thicker specimens, providing external surface details.
When comparing Magnification and Resolution in electron microscopy, both TEM and SEM offer substantial magnification over traditional optical microscopes, with TEM providing higher magnification and resolution and SEM offering adequate magnification with lower resolution but the added benefit of three-dimensional surface imaging.