Temperature dependence of the quenching of vibrationally excited N2 by NO and H2O

Abstract

A photoionization technique for the detection of vibrationally excited nitrogen (N₂*) has been applied to study the quenching of N₂* (v=1) by NO and H₂O over the temperature range 300 to 993°K using a flow system with microwave excitation of the nitrogen. The rate coefficient for quenching of N₂* (v=1) by NO is found to be (2.2±0.9) ×10⁻¹⁵ cm³ sec⁻¹ at 293°K, (3.2±1.3) ×10⁻¹⁵ cm³ sec⁻¹ at 525°K, (6.5±2.5) ×10⁻¹⁵ cm³ sec⁻¹ at 700°K, and (1.6±0.6) ×10⁻¹⁴ cm³ sec⁻¹ at 993°K. These rate coefficients are in reasonable agreement with previous measurements and are the first measurements in the 500 to 993°K range. The rate coefficient for quenching of N₂* (v=1) by H₂O is found to be (1.2±0.5) ×10⁻¹⁴ cm³ sec⁻¹ at 293°K, (2.5±1) ×10⁻¹⁴ cm³ sec⁻¹ at 523°K, (5.1±2) ×10⁻¹⁴ cm³ sec⁻¹ at 693°K, and (1.1±0.4) ×10⁻¹³ cm³ sec⁻¹ at 963°K. These data are also in reasonable agreement with published acoustic, impact tube, and shock tube measurements.