报告摘要：
　　Chemically reactive atmospheric species play a crucial role in tropospheric processes that dominate regional air quality and global climate change. Contrary to long-lived species (such as greenhouse gases), real time in situ sensing such short-lived atmospheric molecules represents a real challenge due to their very high reactivity resulting in short lifetimes (of around 1-100 seconds) and ultra-low concentrations that measure in parts per billion by volume (ppbv) to parts per quadrillion by volume (ppqv).
　　In this talk, we will overview our recent progress in instrumental developments for trace gas monitoring of nitrous acid (HONO), nitrate radical (NO₃), hydroxyl free radical (OH) and nitrogen dioxide (NO₂) with the help of advanced photonic technologies (such as quantum cascade laser, difference-frequency generation parametric source, light emitting diode in conjunction with long optical path length enhanced absorption spectroscopy). The experimental arrangements, their applications to field observation and smog chamber study will be presented.