Photoelectron Spectroscopy and Theoretical Study of Cr_nSi_15–n^– (n = 1–3): Effects of Doping Cr Atoms on the Structural and Magnetic Properties

Abstract

Cr n Si15–n – (n = 1–3) clusters were investigated by using size-selected anion photoelectron spectroscopy combined with density functional theory calculations. The results show that the most stable structure of CrSi14 – is of C 2v symmetry with the Cr atom encapsulated in a Si14 cage which can be viewed as a boat-shaped Si10 unit capped by four additional silicon atoms. A large HOMO–LUMO gap of neutral CrSi14 is confirmed based on the photoelectron spectrum of CrSi14 – anion. Cr2Si13 – has two isomers nearly degenerate in energy: one can be characterized as one Si atom interacting with a Cr2Si12 hexagonal prism while the other can be viewed as one Si atom capping a distorted Cr2Si12 hexagonal antiprism. Cr3Si12 – has a D 6d symmetric wheel structure in which three Cr atoms form an axle surrounded by 12 Si atoms. The magnetic moments of CrSi14 –, Cr2Si13 –, and Cr3Si12 – increase from 1 to 3 μB and then to 7 μB with the increasing number of Cr atoms in the clusters. The magnetic moments of Cr2Si13 – and Cr3Si12 – are mainly contributed by the surface Cr atoms.

Endohedrally Doped Cage Clusters

“…The photoelectron spectra of anionic silicon clusters have been studied experimentally since 1987, 500−502 while extensive measurements of the photoelectron spectra of a rich variety of metal doped silicon clusters have been carried out by Nakajima's group, 54,55,485−487 Bowen's group, 490−492 and Zheng's group. [431][432][433][442][443][444]453,454,460,466 These include the photoelectron spectra of anionic [MSi n ] − clusters in a wide size range, including [TbSi n ] − (n = 6−16), 485 [TiSi n ] − (n = 8−18), 54 . 466 From such experiments on anionic clusters, one can determine the threshold energy of electron detachment, which gives the AEA of the corresponding neutral cluster.…”

“…In addition to the singly doped silicon clusters, the same group also reported the photoelectron spectra of anionic silicon clusters doped with two or three transition metal atoms, such as 444 and [Cr x Si 15−x ] − (x = 1−3). 460 The essential information about the atomic and electronic structures of these clusters from the combined photoelectron spectroscopy and DFT studies will be discussed in Section 5. 3.…”

Electronic structure and bonding in endohedral Zintl clusters

“…Our focus in this review will be firmly on endohedral Zintl clusters [32][33][34][35][36][37] that are primarily the domain of synthetic inorganic chemistry and, very recently, materials science, but they have also been the subject of many theoretical and gas-phase spectroscopic studies. [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] Generally, Zintl clusters are anionic molecules made up of atoms from p-block (semi)metals. More specifically, the title of this article narrows the focus further to endohedral clusters, in which a single atom or ion of the d-or fblock elements is encapsulated within a cluster shell comprising a much larger number of p-block (semi)metal atoms from groups 13 to 15.…”

The study on the reaction of gas-phase Cr<sub><italic>x</italic></sub>N<sup>−</sup> (<italic>x=</italic>2–7) anion clusters with CO<sub>2</sub>

“…在14种测试方法 中BLYP和B1B95均可很好地预测Cr-Cr、Cr-N、 Cr-O、C-O和N-O键的键解离能(表S1, 附加材料), 但 BLYP能够计算出更准确的Cr-Cr键能, 因此本文采用 BLYP方法. 其他含铬配合物也采用相同的方法获得 了可信的结果 [57,58] . 为了探究不同基组的影响, 我们 测试了较大的基组, 即对铬原子使用def2-QZVP [59] , 对…”