Molecular Science: The study of the physics of molecular interactions.
The study of molecules can be focused on the chemistry of molecular interactions, or the physics of the interactions. Molecules are composed of two or more atoms, and the properties and structure of how they interact is studied by molecular physicists and biologists. A molecular chemist will study the making and breaking of the chemical bonds between molecules while a molecular physicist may study structures on earth or take measurements of electromagnetic fields given off by stars and planetary clusters.
Since the atoms are connected by chemical bonds, even a profession of molecular physics
encompasses a broad spectrum of knowledge including chemistry, biology and molecular dynamics. Structures are frequently studied using spectroscopy for chemical and crystallography for biological ones. Study of space bodies requires measuring wavelengths of different celestial bodies that reach Earth.
Atomic physics, which is very closely related, entails the study of atoms within molecules. This is different from understanding the structure of molecules, but may be necessary to understand their properties. This may be considered as it’s own field or as part of the requirements of molecular physics.
Molecules have energy levels, rotations and vibrations. These properties will vary depending on which molecules are associated and the structure in which they reside. The properties can be measured using an electromagnetic spectrum. While very long wavelengths can be measured as color, the smaller wavelengths given off by the rotational states of molecules can only be measured by very precise machines know as a spectrometer or a spectral analyzer.
Molecular science therefore encompasses the physical, chemical, optical and electromagnetic properties of molecules and is a very broad field.