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Phototelectric Emission Measurements on the Analogs of Individual Cosmic Dust GrainsThe photoelectric emission process is considered to be the dominant mechanism for charging of cosmic dust grains in many astrophysical environments. The grain charge and the equilibrium potentials play an important role in the dynamical and physical processes that include heating of the neutral gas in the interstellar medium, coagulation processes in the dust clouds, and levitation and dynamical processes in the interplanetary medium and planetary surfaces and rings. An accurate evaluation of photoelectric emission processes requires knowledge of the photoelectric yields of individual dust grains of astrophysical composition as opposed to the values obtained from measurements on flat surfaces of bulk materials, as it is generally assumed on theoretical considerations that the yields for the small grains are much higher than the bulk values. We present laboratory measurements of the photoelectric yields of individual dust grains of silica, olivine, and graphite of approximately 0.09 to 8 microns radii levitated in an electrodynamic balance and illuminated with W radiation at 120 to 160 nm wavelengths. The measured values and the size dependence of the yields are found to be substantially different from the bulk values given in the literature.
Document ID
20050237036
Document Type
Preprint (Draft being sent to journal)
Authors
Abbas, Mian M. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Tankosic, D.
Craven, P. D.
Spann, J. F.
LeClair, A.
West, E. A.
Weingartner, J. C.
Tielens, A. G. G. M.
Nuth, J. A.
Camata, R. P.
Gerakines, P. A.
Date Acquired
August 23, 2013
Publication Date
January 1, 2005
Subject Category
Astrophysics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.