Cotterell MI, Knight JW, Reid JP, Orr-Ewing AJ. Accurate Measurement of the Optical Properties of Single Aerosol Particles Using Cavity Ring-Down Spectroscopy.
J Phys Chem A 2022;
126:2619-2631. [PMID:
35467353 PMCID:
PMC9082593 DOI:
10.1021/acs.jpca.2c01246]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
New approaches for
the sensitive and accurate quantification of
aerosol optical properties are needed to improve the current understanding
of the unique physical chemistry of airborne particles and to explore
their roles in fields as diverse as chemical manufacturing, healthcare,
and atmospheric science. We have pioneered the use of cavity ring-down
spectroscopy (CRDS), with concurrent angularly resolved elastic light
scattering measurements, to interrogate the optical properties of
single aerosol particles levitated in optical and electrodynamic traps.
This approach enables the robust quantification of optical properties
such as extinction cross sections for individual particles of known
size. Our measurements can now distinguish the scattering and absorption
contributions to the overall light extinction, from which the real
and imaginary components of the complex refractive indices can be
retrieved and linked to chemical composition. In this Feature Article,
we show that this innovative measurement platform enables accurate
and precise optical measurements for spherical and nonspherical particles,
whether nonabsorbing or absorbing at the CRDS probe wavelength. We
discuss the current limitations of our approach and the key challenges
in physical and atmospheric chemistry that can now be addressed by
CRDS measurements for single aerosol particles levitated in controlled
environments.
Collapse