Dissociation Patterns of Small FemOn+ (m = 1–4, n  6) Cluster Cations Formed Upon Chemical Ionization of Fe(CO)5/O2 Mixtures

Collision-induced dissociation studies of FemOn+ : Bond energies in small iron oxide cluster cations, FemOn+ (m=1–3, n=1–6)

“…In better agreement with the present results, Schröder et al observe reaction ͑16͒ dominating the products, with about twice as much intensity as reaction ͑15͒, and only minor amounts of reactions͑17͒ and ͑18͒. 32 Photodissociation yields reactions͑15͒, ͑16͒, and ͑18͒, with the latter dominating. 34 According to the observed dissociation cross sections for Fe 2 O 4 + , reactions ͑19͒ and ͑20͒ can be recognized as primary dissociation channels, whereas reactions ͑21͒-͑24͒ involve secondary dissociation from the primary Fe 2 O 2 + product ion.…”

“…Both of the cross sections remain relatively flat at higher energies with ͑Fe + ͒ being favored by about a factor of 4 compared to ͑FeO + ͒. This behavior is consistent with the observations of Reilly et al 33 who report both of these products and Schröder et al 32 who find twice as much Fe + as FeO + .…”

“…As first noted by Schröder et al, 32 the oxidation state of iron correlates with the observed dissociation patterns of the iron oxide clusters investigated here. From a qualitative point of view, Schröder et al find that low-valent Fe m O n + clusters ͑m / n Ͼ 1͒ tend to lose FeO.…”

“…In agreement with our results, Schröder et al observe reaction ͑28͒ as the dominant product, with appreciable amounts of reaction ͑29͒ and Fe 3 O 2 + as well. 32 Likewise, photodissociation produces all three product ions seen here, although Fe + is found as the dominant species. 34 Six products are observed for the CID of Fe 3 O 4 + , as shown in Fig.…”

“…2͑d͒, although the Fe 2 O 3 + product is slightly more prominent. Neither Schröder et al 32 nor Reilly et al 33 report results for these two species, however, in the latter study, both "n =2-4… +Xe Three clusters having three iron centers are generated in the ion source, Fe 3 O n + ͑n =2-4͒. Figure 3 shows the CID cross sections with Xe as a function of kinetic energy for these species.…”