Experimental evaluation of the gas-phase collision cross-section of effusive Au beam with noble gases: The effect of size and flux

• Gas-phase collision between Au and noble gases is quantitatively evaluated.
• The collision cross section is proportional to the atomic radii of noble gases.
• The cross-sectional radii explain a long-range van der Waals interaction.

We find that the effusive atomic beam of Au atoms is deflected away by collision with noble gas atoms crossing in a perpendicular geometry with a beam flux of >1 × 1016/cm2s. The ratio of defected Au atoms is found to increase proportional to the flux of noble gases. In addition, the effective cross-section for the collision between Au and noble gases (Ne, Ar, Xe) is measured to increase in an order of Ne < Ar < Xe. As a result of the increased collision probability, the deflection ratio of Au beam in the noble gases is measured to be enhanced for the Au flux in the range of 1 × 1011–1013 Au/cm2s. Our results show that the gas-phase collision can be reliably determined by measuring the deflection ratio. The experimentally determined collision cross-section also explains the variation in the deflection ratio among various noble gases and the importance of a long-range van der Waals interaction between Au and noble gases in the deflection efficiency.