Hg adsorption on optically thin Au films

Journal Article · Tue May 01 04:00:00 UTC 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.344948· OSTI ID:6950298

Butler, M A; Ricco, A J; Baughman, R J ^[1]

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1. Sandia National Laboratories, Albuquerque, New Mexico 87185 (USA)

Monitoring the reflectivity of optically thin Au films on the ends of multimode optical fibers during exposure to Hg vapor provides a new means of determining the nature and extent of chemisorption and reaction of Hg with Au. Upon Hg vapor exposure, a freshly deposited Au film shows an initial increase in reflectivity, followed after some time by a substantial reflectivity decrease. The initial reflectivity increase is a result of the chemisorption of Hg on the Au, augmenting the film's optical thickness. The subsequent reflectivity decrease, which is observed only for saturated or near-saturated Hg vapor concentrations ({ital p}/{ital p}{sub sat} {gt}0.1), is a consequence of amalgamation of the Au by the Hg. The amalgamation process, which begins at grain boundaries when multilayers of Hg exist on the surface of the Au, results in the formation of large voids in the Au film. Energy-dispersive x-ray fluorescence spectroscopy shows the resulting amalgam to have the approximate composition Au{sub 2} Hg{sub 3}. Reflectivity measurements have been made as functions of Hg partial pressure and of Au film thickness; models are presented which describe both behaviors. Detection of Hg vapor in the parts per 10{sup 9} concentration range has been demonstrated, suggesting that this effect could be used to monitor Hg vapor concentrations at the Occupational Safety and Health Administration exposure limits.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6950298
• Journal Information: Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 67:9; ISSN 0021-8979; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ADSORPTION
ALLOYS
ELECTROMAGNETIC RADIATION
ELEMENTS
FIBERS
FILMS
FLUORESCENCE
GOLD
IONIZING RADIATIONS
LUMINESCENCE
MERCURY
MERCURY ALLOYS
METALS
OPTICAL FIBERS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
REFLECTIVITY
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS
X RADIATION