Abstract: An ATR-spectrometer has an ATR-crystal which includes a truncated conical section and two planar surfaces that are arranged in parallel to each other, an emitter configured to emit electromagnetic radiation via one of the surfaces to a lateral surface of the truncated conical section configured to reflect the electromagnetic radiation to propagate in the ATR-crystal by a plurality of reflections and to subsequently couple out of the ATR-crystal, and a detector configured to detect the electromagnetic radiation coupled out. The one of the surfaces includes an in-coupling region for coupling in the electromagnetic radiation. The in-coupling region is a projection of a circumferentially extending section of the lateral surface to the one of the surfaces. The emitter has an electromagnetic radiation emitting surface, the projection of which on the in-coupling region exceeds, seen from a center point of the one of the surfaces, an angle (?) of at least 1.5°.