Laser trapping of small colloidal particles in a nematic liquid crystal: Clouds and ghosts

We show that, contrary to intuition, small (< or =1 microm) transparent particles can be trapped and manipulated in a nematic liquid crystal using an intense laser beam, although their index of refraction is lower than both refractive indices of the surrounding birefringent fluid. Two mechanisms...

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Bibliographic Details
Published in:	Physical review letters Vol. 93; no. 18; pp. 187801.1 - 187801.4
Main Authors:	MUSEVIC, I, SKARABOT, M, BABIC, D, OSTERMAN, N, POBERAJ, I, NAZARENKO, V, NYCH, A
Format:	Journal Article
Language:	English
Published:	Ridge, NY American Physical Society 29-10-2004
Subjects:	Condensed matter: structure, mechanical and thermal properties Exact sciences and technology Liquid crystals Orientational order of liquid crystals; electric and magnetic field effects on order Physics Structure of solids and liquids; crystallography Melting Fine particle Laser radiation Birefringence Liquid crystals Nematic crystals Silica Particle trapping
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Summary:	We show that, contrary to intuition, small (< or =1 microm) transparent particles can be trapped and manipulated in a nematic liquid crystal using an intense laser beam, although their index of refraction is lower than both refractive indices of the surrounding birefringent fluid. Two mechanisms are identified that are responsible for this anomalous trapping: (i) surface-induced distortion of the birefringent media around the particle, creating a high-index "cloud" around the colloid, and (ii) laser-induced distortion or (partial) melting of a nematic, creating a ghost colloid.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0031-9007 1079-7114
DOI:	10.1103/physrevlett.93.187801