The Institute for Spectroscopy Russian Academy of Sciences (ISAN) (in some sources the abbreviation used is ISAS, IS RAS) is a Russian research institution located in Troitsk, Moscow region. At present (2013) ISAN has eight research departments, which activity covers practically all kinds of spectroscopies: atomic, molecular, plasma, gases, liquids, condensed matter, amorphous solids, glasses, crystals, nanostructures, polymers, biological systems. The available equipment allows for measurements in a broad spectral range; with ultimate spectral, spatial and temporal resolutions; in a broad range of temperatures and measurement times; with application of external fields. ISAN educational activity includes a program for Diploma Students, Ph.D. and Doctorals for science, R&D and industry. The "Chair of Quantum Optics" of the Moscow Institute of Physics and Technology is based at ISAN.