Molybdenum carbide, nitride, and sulfide clusters were created via laser ablation in the presence of dilute and neat reactive carrier gases. Distributions of the neutral products were characterized by time-of-flight mass spectrometry after photoionization with 193 nm radiation. The carbide clusters show an increase in ion intensity up to Mo 8 C 12 at which point there is a sharp drop in intensity. The latter suggests that the Mo 8 C 12 neutral or ion is particularly stable, which we attribute to a Met-Car-like structure analogous to that observed for other early transition-metal carbides. Carbide clusters containing 10-23 Mo atoms exhibit a Mo x C x+3 stoichiometry, while those containing >23 Mo atoms are closer to Mo x C x+2 , indicative of near cubic nanocrystallite structures. At low mass (Mo x , x e 6), cluster ions produced in expansions of ammonia gas contained up to three nitrogen atoms; however, heavier species (Mo x , x e 40) appear to be pure molybdenum metal clusters. The mass distributions for the sulfide clusters indicate a "magic number" structure at Mo 6 S 4 + which is attributed to a stable structure previously observed for the [Cu 6 S 4 ]anion. Also, the dependence of cluster distributions on the fluence of the ionizing laser was investigated to gain insight on the observed cluster ion distributions using a simple, qualitative kinetic model.
Comparison of density functionals for energy and structural differences between the high-[ 5 T 2g :(t 2g) 4 (e g) 2 ] and low-[ 1 A 1g :(t 2g) 6 (e g) 0 ] spin states of iron(II) coordination compounds. II. More functionals and the hexaminoferrous cation, [ Fe (NH 3) 6 ] 2+ We analyze the low-energy electronic structure of a series of symmetric cationic diarylmethanes, which are bridge-substituted derivatives of Michler's Hydrol Blue. We use a four-electron, three-orbital complete active space self-consistent field and multi-state multi-reference perturbation theory model to calculate a three-state diabatic effective Hamiltonian for each dye in the series. We exploit an isolobal analogy between the active spaces of the self-consistent field solutions for each dye to represent the electronic structure in a set of analogous diabatic states. The diabatic states can be identified with the bonding structures in classical resonance-theoretic models of cyanine dyes. We identify diabatic states with opposing charge and bond-order localization, analogous to the classical resonance structures, and a third state with charge on the bridge. While the left-and right-charged structures are similar for all dyes, the structure of the bridge-charged diabatic state, and the Hamiltonian matrix elements connected to it, change significantly across the series. The change is correlated with an inversion of the sign of the charge carrier on the bridge, which changes from an electron pair to a hole as the series is traversed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.