Based on the thermal decomposition of nitrogen pentoxide(N_2O_5)and the thermal balance relationship between N_2O_5 and NO_3free radical,the concentrations of N_2O_5 and NO_3free radical are measured by cavity ringdown spectral technology.In view of the reversible balance between NO_2 and N_2O_5,the influences of heating temperature and NO_2 concentration on decomposition rate of N_2O_5 are investigated.Considering the loss of N_2O_5 in the measurement system,the inlet efficiency obtained by the preliminary...