On the image formation in x-ray radiography using aligned carbon nanofibers

- Field-emission (FE) x-ray radiography (XR) is based on nanotechnology.
- FE-XR surpasses thermionic XR in image resolution and brilliance.
- Highly-resolved FE-XR images are due possibly to a discrete array of x-ray spots.
- This hypothesis stimulates open discussion on how to define the focal-point in FE-XR.

Evidence is presented that field electrons emitted from vertically-aligned carbon nanofibers (CNFs) yield clearer x-ray images than do thermionic electrons, under the identical electron-optical condition. Specifically, the same sample, an LSI circuit, mounted on the same x-ray chamber could be imaged far more sharply with a CNF emitter than with a thermionic one. It is hypothesized that electrons discharged from CNF tips hit the target to form “discrete focal points” thereon, thereby generating multiple x-ray beams that interplay to form a brilliant, sharply-delineated x-ray image. This hypothesis may stimulate open discussion on how to define the “focal point” for the x-ray imaging using nano-structured electron sources. Also, the improved resolution attained with CNFs might indicate that the heat generation originating in electron-target interactions is not so serious in the present field-emission mode.