Glow discharges (GDs), either coupled to optical emission or to mass spectrometry, have been widely investigated during the last three decades for a high variety of direct solid analytical applications. The intrinsic characteristics of these techniques, e.g. low matrix effects, multi-elemental capabilities, analytical sensitivity and good depth resolution, explain the continuous effort towards new developments aiming at further broadening their applications field and, so, the interesting applications reported so far. In this chapter, a brief description of the basics of the GDs is given first. Most recent instrumental advances will be then described in detail, both for optical emission and mass spectrometry, together with the analytical improvements that these instrumental progresses have allowed. Particular interest is paid to GD time-of-flight mass spectrometry, as this instrumentation (commercially launched in 2014) has proved to be promising in terms of high depth resolution, fast acquisition rates and time-gated detection, showing also interesting capabilities to obtain both elemental and molecular information. Finally, recent applications of GD techniques are described (focusing on the last five years). Special attention is given to the characterization of advanced materials such as multilayers, thin film solar cells and polymers.
Keywords: Depth profile analysis, Direct solid analysis, Elemental analysis, Glow discharge, Mass spectrometry, Multi-matrix calibration, Multilayers, Optical emission spectrometry, Thin films, Time of flight.