Destruction of a MgF sub 2 optical coating by 250 keV. alpha. particle irradiation

Journal Article · Mon Oct 22 00:00:00 EDT 1990 · Applied Physics Letters; (USA)

DOI:https://doi.org/10.1063/1.104141· OSTI ID:6082676

Mendenhall, M H; Weller, R A ^[1]

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1. Vanderbilt University, Nashville, Tennessee 37235 (USA)

Magnesium fluoride coatings {similar to}170 A thick have been evaporated onto mirror-quality Be substrates in ultrahigh vacuum and subsequently subjected to 250 keV {alpha} particle irradiation at room temperature. Analysis of the irradiated area by medium energy backscattering spectrometry revealed that the irradiation selectively removed fluorine with an initial yield of 2.2 fluorine atoms per incident {alpha} particle. A visible degradation in reflectivity, which became progressively more extensive with increasing dose, was observed after an {alpha} particle fluence of 10{sup 16} cm{sup {minus}2}. After a total irradiation of 4{times}10{sup 17} cm{sup {minus}2} less than 20% of the fluorine in the film remained, effectively reducing it to metallic magnesium. The effect of this change on the reflectivity of the surface was catastrophic.

• OSTI ID: 6082676
• Journal Information: Applied Physics Letters; (USA), Journal Name: Applied Physics Letters; (USA) Vol. 57:17; ISSN APPLA; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360605* -- Materials-- Radiation Effects
ALKALINE EARTH METAL COMPOUNDS
ALPHA PARTICLES
CHARGED PARTICLES
ENERGY RANGE
FILMS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
KEV RANGE
KEV RANGE 100-1000
MAGNESIUM COMPOUNDS
MAGNESIUM FLUORIDES
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
REFLECTIVITY
SURFACE PROPERTIES
THIN FILMS