School of Resources and Environment,Henan Polytechnic University
Key Laboratory of Deep⁃Earth Dynamics of Ministry of Natu⁃ral Resources,Institute of Geology,Chinese Academy of Geological Sciences
College of Earth and Planetary Sciences,University ofChinese Academy of Sciences
Department of Science and Technology of Shanxi Province

Coals are a special kind of organic rocks,which are mainly composed of macromolecule polymer. Accu⁃rate description and quantitative characterization on the structural characteristics of coal macromolecules can provideimportant information for understanding the evolution mechanism of coal structure. Raman spectroscopy is a fastand non⁃destruction approach to characterize carbonaceous materials,which has been widely used in the characteriza⁃tion of coal macromolecular structures. The research progress of Raman spectroscopy in the characterization of coal macromolecules both in China and abroad was systematically analyzed and summarized. ① For the Raman spec⁃trum test of coals,some sample processing methods including the epoxy resin molding and polishing,the selectionof different laser light sources,laser energy and signal collection time will affect Raman results. In addition,the coalrank and the structural information contained in the peak of the Raman spectrum should be fully considered in peakfitting. ② The effect of temperature on the structural evolution of organic in coals can be divided into two stages:theRaman spectrum changes irregularly before graphitization and the Raman disorder parameters graduallydecrease during high⁃temperature graphitization. Under high⁃pressure and normal temperature, the Ramancharacteristic peaks linearly shift to higher frequencies,which is consistent with the change of Raman spectrum re⁃sponse to stress,and the structural defects caused by tectonic stress will reduce the structural order degree of coal⁃based graphite. ③ There is no strict corresponding relation between Raman disorder parameters and coalification,which are suggested to be closely related to many factors,including the asynchronous evolution between coal macromo⁃lecular structure and chemical structure,and the effect of stress on structure ordering by inducing structure defects.④ Other applications include the calculation of aromatic layer size,the indication of special peaks and the use of sec⁃ond⁃order Raman spectroscopy in the characterization of coal structure. However, these parameters need to beused carefully in practice.