In this paper, a dedicated ion mobility spectrometer for heavy element research will be presented. Like most advanced mobility spectrometers, the presented apparatus is equipped with a mass spectrometer for isotope-selective detection. In addition, the sample atoms are ionized by exploiting the element-selective laser resonance ionization techniques. First systematic studies at various lanthanide elements have shown that their low-field mobilities in argon are quite similar. The only exception is the element gadolinium, which exhibited an 8% lower reduced mobility of 1.692(24) cm 2 /V s. This anomaly is assumed to be a direct consequence of occupying the d - instead of an f -orbital in singly charged gadolinium, which in turn has a significant impact on the gadolinium-argon interaction potential.