Skip to content

Aerosol optical chromatography and measurements of light extinction by single particles

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Publisher or commissioning bodySociety of Photo-Optical Instrumentation Engineers (SPIE)
Volume9164
ISBN (Print)9781628411911
DOIs
DatePublished - 2014
EventOptical Trapping and Optical Micromanipulation XI - San Diego, United States
Duration: 17 Aug 201421 Aug 2014

Conference

ConferenceOptical Trapping and Optical Micromanipulation XI
CountryUnited States
CitySan Diego
Period17/08/1421/08/14

Abstract

To resolve some of the significant uncertainties in the impact of aerosols on global climate, new tools are required to probe light scattering and absorption by aerosol particles. Ideally, such tools should allow direct measurements on individual particles over extended periods of time, providing data to better constrain the optical properties of aerosol, how they depend on the environmental conditions (relative humidity and temperature) and how they change with time. Here, we present a new technique using a combination of a Bessel beam to manipulate individual particles and cavity ringdown spectroscopy for ultrasensitive measurements of the optical extinction. We show that particles can be spatially separated along the propagation direction of a Bessel beam according to their size and refractive index when confined by a Bessel beam core and a counter-propagating gas flow, referred to as optical chromatography. The time-dependent position of a particle is shown to be a consequence of the differing size dependencies of the forces arising from Stokes drag and radiation pressure. We also show that particles captured in a Bessel beam can be moved in and out of an optical cavity formed by two highly reflective mirrors. The time constant for the ringdown in light coupled within the cavity can then be used to measure the optical cross-section of the individual particle with high accuracy. An individual particle can be captured indefinitely and its change in optical cross-section measured with change in environmental conditions.

    Research areas

  • aerosols, Bessel beam, cavity ringdown spectroscopy, light scattering and extinction, optical chromatography, Optical trapping and manipulation

Event

Optical Trapping and Optical Micromanipulation XI

Duration17 Aug 201421 Aug 2014
CitySan Diego
CountryUnited States
SponsorsThe Society of Photo-Optical Instrumentation Engineers (SPIE) (External organisation)

Event: Conference

Documents

DOI

View research connections

Related faculties, schools or groups