Photothermal spectroscopy of aerosols

Conference · Wed Apr 01 04:00:00 EST 1981

OSTI ID:6062831

Campillo, A J; Lin, H B

In situ aerosol absorption spectroscopy was performed using two novel photothermal detection schemes. The first, based on a photorefractive effect and coherent detection, called phase fluctuation optical heterodyne (PFLOH) spectroscopy, could, depending on the geometry employed, yield particle specific or particle and gas absorption data. Single particles of graphite as small as 1 ..mu..m were detected in the particle specific mode. In another geometrical configuration, the total absorption (both gas and particle) of submicron sized aerosols of ammonium sulfate particles in equilibrium with gaseous ammonia and water vapor were measured at varying CO/sub 2/ laser frequencies. The specific absorption coefficient for the sulfate ion was measured to be 0.5 m/sup 2//g at 1087 cm/sup -1/. The absorption coefficient sensitivity of this scheme was less than or equal to 10/sup -8/ cm/sup -1/. The second scheme is a hybrid visible Mie scattering scheme incorporating photothermal modulation. Particle specific data on ammonium sulfate droplets were obtained. For chemically identical species, the relative absorption spectrum versus laser frequency can be obtained for polydisperse aerosol distributions directly from the data without the need for complex inverse scattering calculations.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6062831
• Report Number(s): BNL-29792; CONF-8104104-1; ON: DE81026098
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ABSORPTION SPECTROSCOPY
AEROSOL MONITORING
AEROSOLS
AMMONIA
AMMONIUM COMPOUNDS
AMMONIUM SULFATES
CARBON DIOXIDE LASERS
COLLOIDS
DISPERSIONS
DISTRIBUTION
FLUIDS
GAS LASERS
GASES
HYDRIDES
HYDROGEN COMPOUNDS
LASERS
MATHEMATICAL MODELS
MONITORING
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
OXYGEN COMPOUNDS
SOLS
SPECTROSCOPY
SULFATES
SULFUR COMPOUNDS
VAPORS
WATER VAPOR