The current invention involves a method and a device for generating and analyzing ions in order to analyze samples directly without sample preparation. The gaseous neutral molecules are desorbed under atmospheric pressure by a desorption method. The desorbed neutral molecules are then transferred into a low pressure region where they are post-ionized by a mist from an electrospray probe tip or by photons from a vacuum UV source. The generated ions are then focused in a time varying electric field in the low pressure chamber before they are transferred into a mass spectrometer or ion mobility spectrometer for further analysis.