Molecular Physics is the study of molecules and their interactions with other particles. It is a subfield of physics that deals with the behavior of matter on the atomic and subatomic level. Molecular physics can be divided into three main branches: spectroscopy, statistical mechanics, and quantum mechanics.
Molecular spectroscopy is the study of how molecules absorb and emit light. This branch of molecular physics is used to determine the structure and properties of molecules. Statistical mechanics is the study of how microscopic particles interact with one another to produce macroscopic phenomena. This branch of molecular physics is used to predict the behavior of gases, liquids, and solids. Quantum mechanics is the study of how molecules behave when they are subjected to external forces such as electric or magnetic fields. This branch of molecular physics is used to understand chemical reactions and make predictions about new materials.
The field of molecular physics has a long history dating back to the early days of modern chemistry in the 19th century. The first molecule that was studied using spectroscopy was water vapor, which was analyzed by English chemist Sir Humphry Davy in 1811. In 1827, German physicist Georg Simon Ohm established that electrical current flows through a material when electrons are able to move freely through it; this discovery laid the foundation for our understanding of electrical conductivity at the atomic level. In 1865, Scottish physicist James Clerk Maxwell formulated his famous equations describing electromagnetic radiation; these equations are still used by scientists today to understand light-matter interactions on a quantum level. In 1873, Austrian physicist Ludwig Boltzmann developed his theory linking entropy (a measure of disorder) with thermodynamic properties such as temperature; this theory helped scientists to understand why some substances are more likely than others to undergo chemical reactions.
The development of quantum mechanics in the early 20th century revolutionized our understanding of molecular behavior. In 1913, Danish physicist Niels Bohr proposed his model for atomic structure, which described atoms as small spheres with electrons orbiting around them like planets around a sun; this model explained why atoms emit or absorb certain wavelengths of light but not others (the so-called “Bohr effect”). In 1925, Austrian physicists Erwin Schrödinger and Werner Heisenberg developed their wave equation and matrix formulation for quantum mechanics, respectively; these two formulations are still used by scientists today to solve problems in molecular physics. In 1927, American chemist Gilbert Noyes experimentally confirmed Bohr’s model for atomic structure by measuring absorption lines in ultraviolet light emitted by sodium atoms; this experiment marked the beginning of experimental verification for many predictions made by quantum theory.
Since its inception, molecular physics has had a profound impact on our understandingof matter on an atomic scale and has led to important advances in both applied scienceand technology