Abstract
A metastable molecule detector having an adjustable detection threshold is described. The metastable molecules are detected through an Auger de-excitation process on a metal surface and the ejected electrons are analysed in an electrostatic retarding field. The maximum kinetic energy of the electrons depends on the excitation energy of the metastable state and this fact in conjunction with the energy analysis is used to achieve the possibility of changing the threshold detection energy. The performance of the detector is illustrated for the case of metastable excitation functions obtained in nitrogen.