Factors affecting improvement of fluorescence intensity of quartet and doublet state of NO diatomic molecule excited by glow discharge*

Abstract

We report on the observation of new fluorescence emission spectral transitions obtained from NO diatomic molecule in the region from ultraviolet (UV) to near infrared (NIR) in a low power glow discharge system. This glow discharge electronic excitation populates different quartet and doublet states of NO in its proximity such as the A 2Σ (υ = 2), b 4Σ− (υ = 3), B 2Π (υ = 4), and X 2Π (υ = 33−32) states. Due to inter-system crossing, emission lines originating from these levels to lower lying states are recorded and spectral line assignments are performed. The observed systems include b 4Σ−−a 4Π, B 2Π−a 4Π, a 4Π−X 2Π, A 2Σ−X 2Π, X 2Π−X 2Π (33–15), X 2Π–X 2Π (33–17), X 2Π–X 2Π (33–20), and X 2Π–X 2Π (33–18). This new information will conduce to the better understanding of the interesting features of NO molecule. Such parameters that affect the recording of low density of NO molecules are also discussed In addition to the factors such as the time evolution, argon gas concentration relative to NO mixture, the percentage of NO molecular gas concentration, discharge electric current signals and discharge applied voltage are studied. Those factors would enhance the fluorescence signal intensity of NO molecules. The recent results might be significant as reference data for optimizing the glow discharge spectrometer and diagnostics of NO gas.