VELOCITY AND MAGNETIC MODULATION METHODS APPLIED TO EMISSION-SPECTROSCOPY

Velocity modulation and magnetic modulation methods as a means of sele ctive modulation of ionic species have been applied for the first time to emission spectroscopy using a grating spectrometer. Magnetic modul ation can achieve concentration modulation effects of up to 100% for i onic species such as N-2(+) at all spectrometer resolving powers. Both neutral and ionic species may be modulated but the depth of modulatio n depends in a non-trivial way on the discharge conditions and region being observed. Velocity modulation in contrast is highly ion specific but the modulation depth depends strongly on the resolving power bein g used. Ion selective spectra using both techniques have been observed for CO+ and N-2(+) in the UV and far-UV regions.