FIGARO: The new horizontal neutron reflectometer at the ILL

Fluid Interfaces Grazing Angles ReflectOmeter (FIGARO) is the new horizontal neutron reflectometer at the Institut Laue-Langevin, Grenoble, France. It is a versatile, high-flux time-of-flight instrument with features suitable for a range of studies in soft condensed matter, chemistry, physics and biology both at free air/liquid interfaces and buried liquid/liquid and solid/liquid interfaces. Most of the experiments exploit isotopic contrast variation to determine the structure and composition of surface layers. Multiple chopper discs allow variable wavelength resolution, with the loose-resolution options increasing the available neutron flux for fast kinetic studies of thin films and improving the data acquisition efficiency from complex samples requiring multiple contrast measurements. It is possible to approach the interface with neutrons from below or above the horizon. The instrument is equipped with a range of sample environments including free liquid adsorption troughs, a Langmuir trough, an overflowing cylinder and a range of solid/liquid sample cells. FIGARO was launched as a user instrument in April 2009 and its success has been steadily increasing since. This article includes an introduction to the scientific case, detailed sections on the instrument components and performance, and descriptions of standard sample environments developed to date as well as some selected early scientific highlights.