Anion Photoelectron Spectroscopy and Density Functional Investigation of Diniobium−Carbon Clusters

Abstract

Experimental photoelectron and computational results show diniobium-carbon (Nb(2)C(n)) clusters to coexist in multiple structural isomers: three-dimensional geometries, planar rings, and linear chains. Three-dimensional clusters having up to five carbons are formed preferentially with Nb-Nb bonding, whereas only Nb-C bonding is observed experimentally at six carbons. Clusters consisting of an odd number of atoms are also observed with linear geometries. The larger binary clusters (n > or = 7) display properties similar to those of pure carbon clusters. We provide evidence for niobium substitution of carbon atoms.

Onset of carbon–carbon bonding in the Nb5Cy(y = 0–6) clusters: a threshold photo-ionisation and density functional theory study

“…[8][9][10][11][12][13][14][15] Since different structural isomers will generally have different ionisation energies, determination of this property helps to guide the search for the lowest energy isomer by either including or excluding potential candidates.…”

“…1,9,[15][16][17][18][19] For example, Castleman and co-workers have recently investigated the structures of anionic Nb 2 C y clusters by a combined photoelectron spectroscopy and DFT study. 15 In particular, they noted that Nb 2 C 5 and Nb 2 C 6 have 3D structures, yet Nb 2 C 7 has a linear structure where a niobium atom is attached to either end of a carbon chain.…”

Versatile cluster based photoelectron spectrometer

“…8,9 Since features are assigned by their zero y intercept, it is necessary to perform background subtraction and baseline leveling and zeroing. This method provides a lower bound for the vertical electron affinity of the cluster.…”

“…8,9 These findings provide significant insight into the interaction between transition metals and carbon and the influence of these interactions on the growth mechanism of larger metal-carbon networks. II a general overview of the experiment is provided and a versatile cluster source is described in Sec.…”

Structural rearrangement in gas phase niobium carbide clusters, Nb C3 and Nb C6

“…Following this discovery, various studies have been performed for niobium carbide clusters to elucidate ionization energies (E i s) [5], electron affinities (E ea s) [6][7][8][9], photodissociation dynamics [10] and reactivity [11][12][13] in combination with density functional theory (DFT) calculations on candidate isomers [14]. Metha et al have conducted photoionization experiments and DFT calculations on niobium carbide clusters with various compositions, Nb 3 C m (m = 1-4), Nb 4 C m (m = 1-6) and Nb 5 C m (m = 0-6) [15,16].…”