Magnetic field effect of the fluorescence of gaseous NO2 excited to the 2B2 and 2B1 states Original Research Article

The effects of an external magnetic field (H) on the integrated intensity and decay of the discrete (Id(H)) and total (It(H)) fluorescence of NO2 vapor were examined under NO2 excitation in the A and B states by pulsed laser-light with different excitation wavelengths and pulse duration (τexc ≈ 10 ns and 100 ps). The fluorescence intensity and decay of NO2 vapor have been measured as functions of external magnetic field strength with excitation in the different spectral regions belonging to the A ⌉ X and B ⌉ X transitions. The integrated fluorescence intensity reduced by an external magnetic field. The relation f(H)(= Id(H)/Id(0)) < r(H)(= It(H)/It(0)) is always satisfied. Field and pressure dependencies of r(H) are in a good agreement with data obtained by Batler and Levy. Field and pressure dependencies of f(H) were carefully studied in the present work. Under microsecond time resolution, the decay can be approximated by an exponential function in the absence and presence of a magnetic field for both the discrete and total fluorescence with respect to the data obtained by Patten et al. In this case, the lifetime of the NO2 fluorescence is not sensitive to the magnetic field within the variability of the excitation wavelength, while the amplitude of the decay decreases in the presence of a magnetic field. Under subnanosecond time resolution, the decay can be presented by a biexponential function in the presence of a magnetic field. The lifetime of the fast component is decreased by the magnetic field. It was directly shown that the fast component induced by the field defines the magnetic quenching of the NO2 fluorescence. These results were explained by the direct mechanism (DM).