Knowledge Bank

The fluorescence from $NO2$ excited by the 4880 \AA line of an argon ion laser has been observed to be partially quenched by the application of a magnetic field. The total fluorescence intensity as a function of magnetic field strength is given by $$ I(H)=\frac{I_{o} A}{A+H^{2}}+B $$\ where A and B are constants. The constant A is independent of pressure over a rather wide range and increases with decreasing pressure at pressure below 1 micron. This is consistent with a new collisional quenching channel being opened by the applied field. The fact that the constant B is non-zero indicates that more than one state is excited by the laser, and that not all states are magnetically quenched.