A method of spectrometry on a spatially extensive sample with generation of a measure in respect of a match of a detected spectrum of a first generation with a single or a plurality of predetermined comparative spectra of chemical substances is disclosed. The method includes the steps: determining at least one location of the first generation on the sample, irradiating the sample with electromagnetic radiation with a plurality of frequencies or a frequency band between 1 GHz and 30 THz at the given location of the first generation of a first order on the sample, frequency-resolved detection of a measure in respect of the intensity of the electromagnetic radiation irradiated on to the sample at the location of the first generation and transmitted or reflected by the sample as the spectrum of the first generation, and calculating a respective measure in respect of a match of the detected spectrum of the first generation with one of the comparative spectra.