In the last years, after the discovery of molecular nanomagnets showing novel quantum effects, a renewed interest for the study of molecular magnetism and multifunctional molecular materials has emerged. These materials have triggered an intense research activity also in view of their possible applicabilities as, for example, as nanosized information storage units and as magnetic nanoparticles for bio-medicine. Several fundamental aspects of the microscopic static and dynamic properties of these molecular materials have been obtained by means of spectroscopies using local probes, as nuclei and muons.In this book an extensive overview on the results obtained during the last decade and on recent achievements in the study of molecular magnets by means of Nuclear Magnetic Resonance, Muon Spin Rotation, Magnetic Resonance Imaging and Mossbauer techniques is presented. The aim is to introduce the reader to these techniques and to give a general background on their application to molecular spin systems.

Nuclear Magnetic Resonance.- A short introduction to Nuclear Magnetic Resonance.- NMR in magnetic single molecule magnets.- Structure, synthesis and characterization of contrast agents for magnetic resonance molecular imaging.- Basic concepts of Magnetic Resonance Imaging.- Phases, phase transitions and spin dynamics in strongly correlated electron systems, from antiferromagnets to HTC superconductors: NMR-NQR insights.- Muon Spin Rotation.- to ?SR.- Muon spin rotation of organic compounds.- Stochastic Landau-Zener model, and experimental estimates of dephasing time in molecular magnets.- Mössbauer Spectroscopy.- Basic principles of Mössbauer spectroscopy and applications.- Line shape of Mössbauer relaxation spectra.- Studies of spin fluctuations in single molecular magnets by using Mössbauer spectroscopy.