Mechanical properties of ultra-thin single crystals for atom-mirror applications: Au(001), Si(001)

Measurements of the mechanical properties of ultra-thin Au(001) and Si(001) crystals are presented. The results for samples with thickness between 2000 Angstrom and 4000 Angstrom are discussed from the perspective of potential applications as optical elements for atomic beams of helium. The membranes were subject to uniform electrostatic pressure and deformation profiles were obtained using phase stepping interferometry. All samples showed mechanical properties dominated by internal stress, which we ascribe to processes in the sample manufacture. Simulations of the focusing properties, using the measured deformation profiles, show that the Si samples give better focal properties, but due to their internal stress they can only provide focal lengths above about 1 m for readily available fields. Imperfections in the Au samples limit their utility to applications requiring short focal lengths of less than approximately 100 mm.