The chemistry of nitrogen oxides on small size-selected cobalt clusters, Con+

Abstract

Fourier transform ion cyclotron resonance mass spectrometry has been employed to study the reactions of gas-phase cationic cobalt clusters, Co(n) (+) (n=4-30), with nitric oxide, NO, and nitrous oxide, N(2)O, under single collision conditions. Isolation of the initial cluster permits detailed investigation of fragmentation channels which characterize the reactions of all but the largest clusters studied. In reaction with N(2)O, most clusters generate the monoxides Co(n)O(+) without fragmentation, cobalt atom loss accompanying only subsequent reactions. By contrast, chemisorption of even a single NO molecule is accompanied by fragmentation of the cluster. The measured rate coefficients for the Co(n) (+)+N(2)O reaction as a function of cluster size are significantly smaller than those calculated using the surface charge capture model, while for NO the rates are comparable. The reactions have been studied under high coverage conditions by storing clusters for extended periods to permit multiple reactions to occur. This leads to interesting chemistry on the surface of the cluster resulting in the formation of stable oxide clusters and/or the decomposition of nitric oxide on the cluster with the resulting loss of molecular nitrogen.

Stability of Aluminum-Doped Copper Cluster Cations and Their Reactivity toward NO and O2

“…This reaction was also observed with or without release of metal atoms for other bare metal and metal oxide clusters such as Co n + , 38,39 Cu n O 2 − , 24 Nb n + , 40 and Rh n ± . 41,42 The NO adsorption probability, the selective activity toward NO [σ r (NO)/σ r (O 2 )], and the NO decomposition efficiency of Cu n Al + are roughly compared with those of Co n + and Cu n O 2 − , which can be obtained mainly from our previous data.…”

NO Decomposition Activated by Preadsorption of O2 onto Copper Cluster Anions

“…9 Likewise, in the reactions of Co n + (n = 2−30) with NO, the observation of NO decomposition is limited to the small clusters (n = 5− 20). 11 As shown in Figure 6, for Cu 8 O 2 − , the first and second NO molecules adsorb on bridge or 3-fold hollow sites, including the Cu atoms interacting with one O atom. On the other hand, such adsorption sites can be prepared neither in the small cluster dioxides with less Cu atoms nor in the highly oxidized clusters with more O atoms, as well as bare Cu clusters.…”

“…A guided ion beam (GIB) study on reactions of Co n + (n = 2−10) with NO by Hanmura et al 12 showed that NO decomposition takes place for n = 5−10, which is confirmed by the subsequent FT-ICR study. 11 These previous studies indicate that dissociative adsorption of NO is the initial and critical step in NO decomposition.…”

“…Similar metal atom release had been observed in the reactions of small Co n + clusters with NO, where NO decomposition proceeds under multiple collision conditions. 11,12 In this further study, we have focused on multiple collision reactions of Cu n O 2 − (n = 8, 10, and 12) with NO. The intensities of reaction product ions are measured by varying the NO gas pressure to find evidence of NO decomposition.…”

Ion–molecule reactions of CoAr6+ with nitrogen oxides N2O, NO, and NO2: measuring absolute pressure by shock-freezing of the collision complex

“…Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is a well suited tool to investigate bimolecular cluster ion-molecule reactions [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In order to determine absolute rate constants one should know the absolute pressure in the ICR-cell accurately, because the pressure is the main uncertainty.…”