Charge state determination

Herron, W.J. Goeringer, D.E. McLuckey, S.A. Product Ion Charge State Determination Via lon/lon Proton Transfer Reactions. Anal. Chem. 1996, 68, 257-262. 

Xiu et al. [23] reported in Bi-doped ZnO films by molecular-beam epitaxy that Bi-induced acceptor ionization energy was estimated to be 0.185-0.245 eV by photoluminescence measurements based on the donor-acceptor pair peak position in the Bi-doped ZnO films Bi in ZnO films had positive charge state determined by X-ray photoelectron spectroscopy measurements, indicating that BiZn at Zn sites, rather than Bio at O sites, was formed in the films. BiZn itself, however, is a donor. The origin of the shallow acceptor states was, therefore, identified as a donor-acceptor pair such as BiZn-VZn-0, or BiZn-2VZn complexes. 

Deep levels can be described by the Shockley-Read-Hall recombination statistics [5]. However, for a large number of deep states, the capture cross section for one type of carrier is many times larger than that for the other carrier. The state, therefore, interacts principally with only one of the band edges and can be characterised as either an electron or a hole trap. Capacitance techniques, such as DLTS (Deep Level Transient Spectroscopy), are particularly convenient for the determination of trap type and concentration. If additional experimental information is present to allow charge state determination, then the states can be characterised as deep acceptors or donors. 

FT-ICRMS is the most effective instrument because the resolution available facilitates spectrum interpretation by enabling charge state determination on highly charged ions. 

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