Optical trapping of nanoshells

Brooke C. Hester, Alice Crawford, Rani B. Kishore, Kristian Helmerson, Naomi J. Halas, Carly Levin

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

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We investigate near-resonant trapping of Rayleigh particles in optical tweezers. Although optical forces due to a nearresonant laser beam have been extensively studied for atoms, the situation for larger particles is that the laser wavelength is far from any absorption resonance. Theory predicts, however, that the trapping force exerted on a Rayleigh particle is enhanced, and may be three to fifty times larger for frequencies near resonance than for frequencies far off resonance.1 The ability to selectively trap only particles with a given absorption peak may have many practical applications. In order to investigate near-resonant trapping we are using nanoshells, particles with a dielectric core and metallic coating that can exhibit plasmon resonances. The resonances of the nanoshells can be tuned by adjusting the ratio of the radius of the dielectric core, r1, to the overall radius, r2, which includes the thickness of the metallic coating.2,3 Our nanoshells, fabricated at Rice University, consist of a silica core with a gold coating. Using back focal plane detection, we measure the trap stiffness of a single focus optical trap (optical tweezers), from a diode laser at 853 nm for nanoshells with several different r1/r2 ratios.

Original languageEnglish
Title of host publicationOptical Trapping and Optical Micromanipulation IV
Publication statusPublished - 1 Dec 2007
Externally publishedYes
EventOptical Trapping and Optical Micromanipulation IV - San Diego, United States of America
Duration: 26 Aug 200729 Aug 2007

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceOptical Trapping and Optical Micromanipulation IV
CountryUnited States of America
CitySan Diego


  • Nanoshell
  • Optical trapping
  • Optical tweezers
  • Plasmon
  • Resonant trapping

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