Dr. Hongming Yi particularly interested in developing spectroscopic techniques from the ultraviolet, visible to the mid-infrared spectral region as well as constructing portable instruments for high-precision trace species measurements using different light sources (LED, diode laser, QCL et al.). Currently, he focuses on cavity ring down spectroscopy (CRDS), Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS) involving differential optical absorption spectroscopy approach for multispecies measurements, Photoacoustic Spectroscopy (PAS), wavelength modulation spectroscopy, Multipass Cell Absorption Spectroscopy (MCAS) and so on. He applied appropriate spectroscopic techniques to study interdisciplinary (such as atmospheric chemistry and physics) open-questions, including investigation of the sinks and sources of atmospheric trace species of NO₂, NH₃, CO, N₂O, NO, CO₂, CH₂O, HONO and CH₄, high-precision determination of absorption lines parameters and isotope ratio of CO₂, studying chemical dynamics of free radicals (NO₃, N₂O₅, and HONO) reaction with volatile organic compounds and particles, and measurements of aerosol optical properties.