Neutron reflectometry instrumentation at the ISIS source: current state

Neutron reflectometry (NR) at the ISIS Neutron and Muon Source has evolved into a mature, versatile technique for investigating the structure and dynamics of interfaces across a wide range of scientific disciplines, including soft matter, magnetism, quantum materials and environmental systems. This article provides a comprehensive overview of the current instrumentation available at ISIS, detailing the capabilities of the four operational reflectometers - OFFSPEC, INTER, POLREF and SURF - including their time-of-flight configurations, scattering geometries, polarization options and range of accessible sample environments. Special emphasis is placed on the integration of advanced sample environments, automated control software and data analysis tools, including IBEX, MANTID and the ISIS Data Analysis as a Service (IDAaaS) platform, which collectively facilitate efficient, reproducible and high-quality NR measurements. Representative scientific highlights demonstrate the unique potential of NR to resolve sub-nanometre structural and kinetic information in biological membranes, thin functional films, quantum fluids and environmental interfaces. By consolidating detailed technical information, operational characteristics and examples of cutting-edge research, this article serves as a practical guide for new and experienced users, helping them design experiments, select suitable instruments and sample environments, and fully exploit the capabilities of ISIS neutron reflectometers.