Search for rare alpha and double beta decays of Yb isotopes to excited levels of daughter nuclei

search for alpha and double beta decays of ytterbium isotopes was performed with an ultra low-background high purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 194.7 g Yb _2 (C _2 O _4 ) _3 powder sample was measured for 11.3 days with a total Yb exposure of 1.25 kg × day. Half-life limits for α -decay modes of ^168Yb , ^170Yb , ^171Yb , ^172Yb , ^173Yb , ^174Yb and ^176Yb into the first excited states have been obtained between 6× 10^14 years and 2× 10^16 years. These are the first experimental constraints of these decay modes. Double electron capture of ^168Yb and double beta decay of ^176Yb into the first excited 2 ^+ and 0 ^+ states could be excluded with limits between 1× 10^14 years to 8× 10^16 years. This improves the experimental information on some of the decay modes compared to previous constraints.