Mixed-metal clusters mass spectra

Figure 9.61 ToF mass spectrum of metal-carbon cluster ions (TiC2+ and ZrnCm+ cluster ions) using a titanium-zirconium (50 50) mixed alloy rod produced in a laser vaporization source (Nd YAG, = 532 nmj and ionization by a XeCI excimer laser (308 ). ( . M. Davis, S. J. Peppernick and A. W Castleman, J. Chem. Phys., 124, 164304(2006). Reproduced by permission of American Institute of Physics.)...

As discussed above, luminescent protein protected clusters exist in solution with zero valent oxidation state of the metal (for example, Au° state for Au clusters). Cluster forms via the metal bound protein complex (Au" -Protein adduct for Au cluster formation) where metal is in its intermediate oxidation state.In this section we will discuss a new class of materials which were observed recently by Baksi et They have observed that when Au -Lyz adducts were subjected to laser ablation, some bare clusters were formed in the gas phase. When Au was mixed with Lyz, Au was uptaken by the protein and a corresponding change is seen in the mass spectrum in the form of appearance of multiple peaks separated by mIz 197 due to Au attachments (Lyz peak appears at mIz 14 300). Maximum 10 Au attachments were observed in the MALDI MS which was justified in terms of limited (eight cysteines forming 4 disulfide bonds) cysteine content. In the lower mass region (<10 kDa), multiple envelopes... 

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