Solvated Electrons in Clusters: Magic Numbers for the Photoelectron Anisotropy

Abstract

This paper reports on a curiosity concerning magic numbers in neutral molecular clusters, namely on magic numbers related to the photoelectron anisotropy in angle-resolved photoelectron spectra. With a combination of density functional calculations and experiment, we search for magic numbers in Na(H2O)n, Na(NH3)n, Na(CH3OH)n, and Na(CH3OCH3)n clusters. In clusters of high symmetry, the highest occupied molecular orbital can be delocalized over an extended region, forming a symmetric charge distribution of high s character, which results in a pronounced anisotropy in the photoelectron angular distribution. We find magic numbers at n = 6 and 4 for sodium-doped dimethyl ether and ammonia clusters, respectively, but not for sodium-doped water and methanol clusters, which is likely a consequence of the degree of hydrogen bonding and the number of structural isomers.

Magic Numbers for the Photoelectron Anisotropy in Li-Doped Dimethyl Ether Clusters

“…High level quantum chemical calculations for Na(CH 3 OCH 3 ) n and Na(NH 3 ) n clusters by Gunina and Krylov 11 are in agreement with our previous experimental results 10,24 and provide a detailed understanding of the underlying phenomena regarding the character of the electronic structure and the influence of structural fluctuations on the electronic properties.…”

“…The experimental setup, the measurement procedures, and the data analysis are essentially identical to those used in our previous investigations of Na(CH 3 OCH 3 ) n clusters. 10,24 For convenience, we repeat here the main aspects as provided in the experimental part of West et al 10 The experimental setup has been previously described in detail. [21][22][23][24][37][38][39] All measurements were performed in a velocity map imaging (VMI) 40,41 photoelectron spectrometer, which can also function as a time-of-flight mass spectrometer.…”

“…The 10 and in the supporting information of West et al 24 Briefly, the highest occupied molecular orbital (HOMO) is expanded in terms of atomic natural orbitals (ANOs). 46 In order to account for the polarization of the HOMO upon solvation we use an expanded valence shell including 2p functions on Li for the ANO analysis (NBO program version 3.1).…”

“…Magic numbers play a central role in cluster science (see references on molecular clusters [1][2][3][4][5][6][7][8][9][10][11][12] ). Usually, these magic numbers are related to the high stability of clusters of certain sizes.…”

“…5,10,11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Typically, a prerequisite for the observation of magic numbers in the photoelectron anisotropy is a high cluster symmetry that results in orbitals with high fractional scharacter. 10,13,14,24 In our recent studies, 10,24 we reported the first observation of magic numbers in the photoelectron anisotropy of solvated electrons in Na-doped clusters of dimethyl ether, ammonia, methanol and water. The studies have revealed that in clusters of high symmetry the solvated electron can delocalize over extended regions, forming symmetric charge distributions of high s-character.…”