Context : M 75 is a relatively young Globular Cluster ( GC ) found at 15 kpc from the Galactic centre at the transition region between the inner and outer Milky Way halos .

Aims : Our aims are to perform a comprehensive abundance study of a variety of chemical elements in this GC such as to investigate its chemical enrichment history in terms of early star formation , and to search for any multiple populations .

Methods : We have obtained high resolution spectroscopy with the MIKE instrument at the Magellan telescope for 16 red giant stars .
Their membership within the GC is confirmed from radial velocity measurements .
Our chemical abundance analysis is performed via equivalent width measurements and spectral synthesis , assuming local thermodynamic equilibrium ( LTE ) .

Results : We present the first comprehensive abundance study of M 75 to date .
The cluster is metal-rich ( [ Fe/H ] = -1.16 \pm 0.02 dex , [ \alpha /Fe ] = +0.30 \pm 0.02 dex ) , and shows a marginal spread in [ Fe/H ] of 0.07 dex , typical of most GCs of similar luminosity .
A moderately extended O-Na anticorrelation is clearly visible , likely showing three generations of stars , formed on a short timescale .
Additionally the two most Na-rich stars are also Ba-enhanced by 0.4 and 0.6 dex , respectively , indicative of pollution by lower mass ( M \sim 4 - 5 ~ { } M _ { \odot } ) Asymptotic Giant Branch ( AGB ) stars .
The overall n-capture element pattern is compatible with predominant r-process enrichment , which is rarely the case in GCs of such a high metallicity .

Conclusions :