抄録
A near-IR laser absorption spectrometer using a technique of wavelength modulation spectroscopy has been used to the measure ammonia (NH_3) and nitrous oxide (N_2O) in automobile exhaust. NH_3 and N_2O were detected at the line center of 6548.60 cm^<-1> (2v_3, ^p_sP(4,3)) and 6549.56 cm^<-1> (3v_3, P(28)e), respectively. To prevent NH_3 from adsorbing on the cell, the cell temperature was set at 373 K. The effect of CO_2 included in automobile exhaust on the concentration of NH_3 and N_2O was evaluated. The air-broadened half-widths of NH_3 (^P_sP(4, 3)) absorption line and the CO_2 - broadened half-widths of NH_3 (^P_sP(4,3)) and N_2O P(28)e absorption lines at 373 K were obtained to be 0.0673 ±0.0101 cm^<-1> atm^<-1>, 0.0941 ±0.0141 cm^<-1> atm^<-1> and 0.0709 ± 0.0106 cm^<-1> atm^<-1>, respectively. Based on these values, the differences in NH_3 and N_2O concentrations between 0% and 16% CO_2 concentration are -2.2% and -1.1%, respectively, which leads to the precise measurements ofNH_3 and N_2O concentrations in automobile exhaust.
