English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

I a recent article Nhat et al. report a comprehensive theoretical study on the structures of small niobium clusters Nbn in different charge states. Structural assignments are presented for the smaller clusters up to n = 9 that largely rely on far-IR vibrational spectra published by us before. For most sizes the structures assigned by Nhat et al. agree with those we identified earlier via comparison of the far-IR spectra with the results ofDFT calculations. Most interesting, however, the authors also make predictions for the structures of larger clusters up to n = 12 and include calculated IR spectra that may allow one to verify the predictions. Although measured simultaneously with the data set reported previously, we had not published the experimental spectra for clusters containing more than nine Nb atoms so far due to the absence of high-quality theoretical spectra to which these could be compared. Therefore we present here the experimental far-IR spectra of Nb10 12 andNb10 12 þ (Figure 1). These size-specific vibrational spectra of gas-phase metal clusters have been measured via far-IR photodissociation of weakly bound complexes of the clusters with single Ar atoms formed at 80 K. For intensity reasons, forNb10 þ and Nb12 the spectra of the complexes with two Ar atoms are reported. The experimental spectra are amended by calculated IR spectra for the structures reported in ref 1 using the meta-GGA functional by Tao, Perdew, Staroverov, and Scuseria. We have shown before that this approach is capable of predicting the IR spectra for this kind of system particularly well. Our recalculated structures and spectra deviate only slightly from the findings of Nhat et al. (Figure 1). The clusters’ geometries are cage-like, i.e., distorted versions of a bicapped anticube (Nb10), a C2v symmetric deltahedron (Nb11), and an icosahedron (Nb12). Comparing experimental and these calculated spectra, we find good agreement for Nb10, Nb11, Nb11 þ, and Nb12 þ. Unfortunately, the quality of the experimental spectra for the cationic clusters in this size range is not exceptionally high; the D4 isomer of Nb10 þ may be present, although the predicted band at 172 cm 1 is hardly visible in the experimental spectrum. Only for the neutral Nb12 cluster do the predictions not match the experimental findings at all and also none of the higher energy isomers reported by Nhat et al. show IR spectra that agree reasonably with the experimental one. Interestingly, we found bands at relatively high frequencies for Nb12, at 293 and 330 cm , whereas all smaller sizes show bands only clearly below 300 cm . The appearance of such high frequency bands can be related to encapsulated atoms, i.e., the formation of structures that do not have all atoms on the surface. In fact, when further exploring the configurations, we find an isomer B with an encapsulated Nb atom that gives convincing agreement with the experimental band pattern, though the relative band intensities do notmatch perfectly. This isomer is 0.26 eV higher in energy than the distorted isocahedron A. Structure B had been predicted as the lowest energy isomer before. Therefore the question arises if our Figure 1. Comparison of experimental IR spectra of Nbn and Nbn þ

the journal of physical chemistry a

Comment on “Electronic Structures, Vibrational and Thermochemical Properties of Neutral and Charged Niobium Clusters Nbn, n = 7–12”