(Aerodynamic focusing of particles and heavy molecules)

Technical Report · Mon Jan 08 04:00:00 EST 1990

DOI:https://doi.org/10.2172/6057314· OSTI ID:6057314

de la Mora, J F

By accelerating a gas containing suspended particles or large molecules through a converging nozzle, the suspended species may be focused and therefore used to write fine lines on a surface. Our objective was to study the limits on how narrow this focal region could be as a function of particle size. We find that, for monodisperse particles with masses m{sub p} some 3.6 {times} 10{sup 5} times larger than the molecular mass m of the carrier gas (diameters above some 100{angstrom}), there is no fundamental obstacle to directly write submicron features. However, this conclusion has been verified experimentally only with particles larger than 0.1 {mu}m. Experimental, theoretical and numerical studies on the defocusing role of Brownian motion for very small particles or heavy molecules have shown that high resolution (purely aerodynamic) focusing is impossible with volatile molecules whose masses are typically smaller than 1000 Dalton. For these, the minimal focal diameter after optimization appears to be 5{radical}(m/m{sub p}) times the nozzle diameter d{sub n}. But combinations of focused lasers and aerodynamic focusing appear as promising for direct writing with molecular precursors. Theoretical and numerical schemes capable of predicting the evolution of the focusing beam, including Brownian motion effects, have been developed, although further numerical work would be desirable. 11 refs.

• Research Organization: Yale Univ., New Haven, CT (USA). Dept. of Mechanical Engineering
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG02-87ER13750
• OSTI ID: 6057314
• Report Number(s): DOE/ER/13750-2; ON: DE91006922
• Country of Publication: United States
• Language: English

Related Subjects

656002* -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AERODYNAMICS
BEAMS
BROWNIAN MOVEMENT
DOCUMENT TYPES
ELEMENTS
FLUID FLOW
FLUID MECHANICS
FOCUSING
MECHANICS
METALS
MOLECULAR BEAMS
PARTICLE BEAMS
PROGRESS REPORT
SIMULATION
SUBSTRATES
SUPERSONIC FLOW