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Proceedings Paper

Toward steering a jet of particles into an x-ray beam with optically induced forces
Author(s): Niko Eckerskorn; Richard Bowman; Richard A. Kirian; Salah Awel; Max Wiedorn; Jochen Küpper; Miles J. Padgett; Henry N. Chapman; Andrei V. Rode
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Paper Abstract

Optical trapping of light-absorbing particles in a gaseous environment is governed by a laser-induced photophoretic force, which can be orders of magnitude stronger than the force of radiation pressure induced by the same light intensity. In spite of many experimental studies, the exact theoretical background underlying the photophoretic force and the prediction of its influence on the particle motion is still in its infancy. Here, we report the results of a quantitative analysis of the photophoretic force and the stiffness of trapping achieved by levitating graphite and carbon-coated glass shells of calibrated sizes in an upright diverging hollow-core vortex beam, which we refer to as an ‘optical funnel’. The measurements of forces were conducted in air at various gas pressures in the range from 5 mbar to 2 bar. The results of these measurements lay the foundation for developing a touch-free optical system for precisely positioning sub-micrometer bioparticles at the focal spot of an x-ray free electron laser, which would significantly enhance the efficiency of studying nanoscale morphology of proteins and biomolecules in femtosecond coherent diffractive imaging experiments.

Paper Details

Date Published: 25 August 2015
PDF: 12 pages
Proc. SPIE 9548, Optical Trapping and Optical Micromanipulation XII, 95480H (25 August 2015); doi: 10.1117/12.2191442
Show Author Affiliations
Niko Eckerskorn, The Australian National Univ. (Australia)
Richard Bowman, Univ. of Glasgow (United Kingdom)
Univ. of Cambridge (United Kingdom)
Richard A. Kirian, Ctr. for Free-Electron Laser Science (Germany)
Arizona State Univ. (United States)
Salah Awel, Ctr. for Free-Electron Laser Science (Germany)
Univ. Hamburg (Germany)
Max Wiedorn, Ctr. for Free-Electron Laser Science (Germany)
Jochen Küpper, Ctr. for Free-Electron Laser Science (Germany)
Univ. Hamburg (Germany)
Miles J. Padgett, Univ. of Glasgow (United Kingdom)
Henry N. Chapman, Ctr. for Free-Electron Laser Science (Germany)
Univ. Hamburg (Germany)
Andrei V. Rode, The Australian National Univ. (Australia)


Published in SPIE Proceedings Vol. 9548:
Optical Trapping and Optical Micromanipulation XII
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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