Using the NIRSPEC spectrograph at Keck II , we have obtained infrared echelle spectra covering the range 1.5 - 1.8 ~ { } \mu m for the moderately reddened bulge globular clusters NGC 6342 and NGC 6528 , finding [ Fe/H ] =–0.60 and –0.17 dex , respectively .
We measure an average \alpha -enhancement of \approx + 0.33 dex in both clusters , consistent with previous measurements on other metal rich bulge clusters , and favoring the scenario of a rapid bulge formation and chemical enrichment .
We also measure very low ^ { 12 } C / ^ { 13 } C isotopic ratios ( \approx 5 in NGC 6342 and \approx 8 in NGC 6528 ) , suggesting that extra-mixing mechanisms due to cool bottom processing are at work during evolution along the Red Giant Branch .