Application of terahertz spectroscopy for remote express analysis of gases

An overview of the main methods of terahertz spectroscopy used for the detection of gases and gas mixtures is presented. Special attention is given to the methods and equipment used for remote express sensing of gases in the atmosphere to ensure a quick and high-precision identification of gases which is a relevant task important both from fundamental and applied points of view. The developed to date methods are analyzed and their parameters, which are largely determined by the available equipment, are discussed. The techniques and equipment used for generation and detection of terahertz radiation are considered including new trends in terahertz technology, emergence of new types of radiation sources, and upgrading of existing ones. Data on the use of the terahertz spectroscopy for the detection of gases in the laboratory and in open air are summarized. Key challenges and prospects for further application of the terahertz spectroscopy are outlined.