BAF

BAF may refer to:

Biology

Resolution Island (Nunavut)

Resolution Island is one of the many uninhabited Canadian Arctic islands in Qikiqtaaluk Region, Nunavut. It is a Baffin Island offshore island located in Hudson Strait. It has an area of 1,015 km² (392 sq mi). The Lower Savage Islands lie between Resolution Island and Baffin Island, while Graves Strait separates Resolution Island from the more northern Edgell Island.

History

English explorer Martin Frobisher landed on the island on July 28, 1576, while on a voyage to discover the fabled Northwest Passage. However it appears to have been named Resolution in 1612 by Sir Thomas Button, after his own ship, the Resolution.

The island was home to an American military base, now CFS Resolution Island, that became operational in 1954 as part of the Distant Early Warning (DEW) line. The base was vacated in 1973 and turned over to the Canadian government in 1974.

The Canadian cargo ship named "MINNA" was wrecked on the east side of the island, on 18 August 1974. The vessel was then under charter by the Bedford Institute of Oceanography and was doing scientific surveys at the time of the accident. Badly damaged, the crew and scientific equipment's were removed. Bad weather swept the vessel in deeper waters where she sank on October 2nd 1974. This vessel with a length of 275 feet's and displacement of 4280 tons was based in Halifax and was on regular charter with the BIO for hydrographic surveys on the Labrador Coast and Hudson Strait. The MINNA was built in 1962 and had a crew of 21 men + 18 scientists.

Barium fluoride

Barium fluoride (BaF₂) is a chemical compound of barium and fluorine and is a salt. It is a solid which can be a transparent crystal. It occurs in nature as the mineral frankdicksonite.

Structure

The solid adopts the fluorite structure and at high pressure the PbCl₂ structure. In the vapor phase the BaF₂ molecule is non-linear with an F-Ba-F angle of approximately 108°. This is an exception to VSEPR theory which would predict a linear structure. Ab initio calculations have been cited to propose that contributions from d orbitals in the shell below the valence shell are responsible. Another proposal is that polarisation of the electron core of the barium atom creates an approximately tetrahedral distribution of charge that interacts with the Ba-F bonds.

Applications

Barium fluoride is transparent from the ultraviolet to the infrared, from 150–200 nm to 11–11.5 µm, and can be used as a material to make optical components such as lenses. It is used in windows for infrared spectroscopy, in particular in the field of fuel oil analysis. Its transmittance at 200 nm is relatively low (0.60), but at 500 nm it goes up to 0.96–0.97 and stays at that level until 9 µm, then it starts falling off (0.85 for 10 µm and 0.42 for 12 µm). The refractive index is about 1.46 from 700 nm to 5 µm.