Spectrum Ni K edge XAS fluorescence of $Ni (H_2O)_6 SO_4$ at 10K Spectrum Ni K edge XAS fluorescence of Nickel(cyclam)acetonitrile perchlorate at 10K Spectrum Ni K edge XAS fluorescence of $Ni NTA(CysNH_2)_3$ at pH=7.5 and at 10K Spectrum Ni K edge XAS fluorescence of $Ni NTA(CysNH_2)_3$ at pH=9.6 and at 10K