Abstract: Microwave spectroscopy, which works at microwave frequencies, developed rapidly in recent years as an analytical tool for studying molecular geometrical structures and intermolecular interactions with high resolution and sensitivity. This review introduces the principles underlying this technique, as well as its applications in studying the weakly bounded complexes, namely van der Waals complexes, hydrogen bond complexes and halogen bond complexes. The pulsed-nozzel Fourier transform microwave spectrometer was also briefly introduced.

Key words: microwave spectroscopy, Fourier transform, supersonic expansion, intermolecular interaction, review