Images of gas molecules by electron holography. II. Experiment and comparison with theory

Abstract

Molecular images photographed by a variant of holographic microscopy proposed in Paper I are presented. ’’Holograms’’ were taken with an electron beam of 0.06 Å wavelength recorded up to a numerical aperture of 0.2 to yield an Abbe resolution limit of 0.15 Å. Experimental requirements and procedures are described. Images, representing rotational averages over an ensemble, closely resemble images calculated according to the theoretical expressions derived in Paper I. The theoretical treatment took into account the degradative effects of the zeroth‐order beam transmitted through the hologram, finite numerical aperture and wavelength, the ’’false’’ peaks arising from the cutoff of the holograms at their centers, and nonoptimum first‐stage filter functions. Illustrative examples include AsF5, a case chosen to satisfy standard holographic requirements, and two cases, SF5Cl and CF3OOCF3, selected to produce more complicated images.