Argon fluorohydride

Argon fluorohydride (HArF) is the first known compound of the chemical element argon.

Discovery
The discovery of this first argon compound is credited to a group of Finnish scientists, led by Markku Räsänen. On 24 August 2000, in the journal Nature, they announced their discovery of argon fluorohydride.

Synthesis
This chemical was synthesized by mixing argon and hydrogen fluoride on to caesium iodide at −265 °C and exposing the mixture to ultraviolet radiation. This causes the gases to react to form argon fluorohydride.

Examining the infrared spectrum of the substance, they found that chemical bonds had formed, albeit very weak ones, so long as the substance was kept at temperatures below −256°C. Upon warming it decomposes into argon and hydrogen fluoride.