A Vacuum Ultraviolet Photoionization Time-of-Flight Mass Spectrometer for Investigation of Free Radical Reaction

Publication date: January 2020Source: Chinese Journal of Analytical Chemistry, Volume 48, Issue 1Author(s): Tao WANG, Xiao-Feng TANG, Zuo-Ying WEN, Cui-Hong ZHANG, Wei-Jun ZHANGAbstractA home-made vacuum ultraviolet (VUV) photoionization linear time-of-flight mass spectrometer (VUVPI-LTOFMS) was utilized to study atmospheric radical reactions. A commercial krypton discharge lamp with photon energy at 10.6 eV was installed as VUV light source and combined with a cage-shape photoionization source to efficiently extract and focus ions. A limit of detection (LOD) of 0.03 μg/L (S/N = 3) for benzene was achieved. A microwave discharge fast flow tube was employed as chemical reactor to produce free radicals and initiate their atmospheric reactions. The concentration of methyl radical was measured with its self-reaction kinetics and the available rate constant. As a representative example, the reaction of the methyl radical with nitric oxide was studied. Both the stable species and radicals involved in the reaction were probed, and the reaction rate constant at room temperature and pressure of 300 Pa was measured to be k(CH3 + NO) = 1.2 × 10−12 cm3/(molecule·s).Graphical abstractA home-made vacuum ultraviolet (VUV) photoionization time-of-flight mass spectrometer (VUVPI-TOFMS) combined with a microwave discharge flow tube was developed to study gas-phase free radical reactions. A commercial VUV discharge lamp with photon energy at 10.6 eV was installed as light source and combin...
Source: Chinese Journal of Analytical Chemistry - Category: Chemistry Source Type: research