Gaschemische

Gaschemische, or gas-phase chemistry, is a branch of physical chemistry that studies chemical processes occurring in the gas phase. It covers reactions among gaseous species, including bimolecular and termolecular reactions, unimolecular decompositions, and radical chain processes. It also includes gas–surface interactions where gases react at interfaces or participate in processes such as chemical vapor deposition.

Research in gaschemische relies on specialized experimental setups such as flow reactors, shock tubes, and rapid compression machines to characterize kinetics under different temperatures and pressures. Detection and analysis use mass spectrometry, laser absorption and fluorescence spectroscopy, and infrared or UV-visible spectroscopy. Theorists use quantum chemistry and statistical mechanics to calculate potential energy surfaces and rate constants, employing transition-state theory, RRKM theory, and master‑equation approaches.

It has applications in combustion science, atmospheric chemistry, and industrial processes such as chemical vapor deposition and plasma-assisted synthesis. In atmospheric chemistry, gas-phase reactions control the formation and destruction of ozone and secondary pollutants through oxidation of volatile organic compounds (VOCs) and NOx chemistry. In materials science, gas-phase processes enable deposition and synthesis of thin films and nanoparticles.

Key challenges include incomplete kinetic data for many radical reactions, the broad range of temperatures and pressures, and the need for accurate modeling of energy transfer and pressure-dependent rate constants.