Formation of Au and tetrapyridyl porphyrin complexes in superfluid helium

Abstract

Binary clusters containing a large organic molecule and metal atoms have been formed by the co-addition of 5,10,15,20-Tetra(4-pyridyl)porphyrin (H2TPyP) molecules and gold atoms to superfluid helium nanodroplets, and the resulting complexes were then investigated by electron impact mass spectrometry. In addition to the parent ion H2TPyP yields fragments mainly from pyrrole, pyridine and methylpyridine ions because of the stability of their ring structures. When Au is co-added to the droplets the mass spectra are dominated by H2TPyP fragment ions with one or more Au atoms attached. We also show that by switching the order in which Au and H2TPyP are added to the helium droplets, different types of H2TPyP/Au complexes are clearly evident from the mass spectra. This study suggests a new route for the control over the growth of metal-organic compounds inside superfluid helium nanodroplets.3

Complexes with Atomic Gold Ions: Efficient Bis-Ligand Formation

“…The ligand most weakly bound to gold is helium [9] and thus ligand-exchange with every other ligand can be expected inside a helium nanodroplet (HND). In the case of neutral helium droplets, this was successfully demonstrated by the growth of pristine and mixed gold clusters containing a few gold atoms [10][11][12][13][14][15][16][17][18], as well as nanoparticles and nanowires that contain many thousand atoms [19][20][21][22][23][24][25]. Recently, we doped neutral HNDs containing about 10 6 He atoms with gold vapor and investigated low-mass ions formed upon electron ionization and ejected from the massive droplets [12].…”

Fluorescent silicon clusters and nanoparticles

“…The methods needed to perform such experiments, such as spectroscopy in droplets of argon (Felix et al, 2001) and helium (Feng et al, 2015;Katzy et al, 2016), have recently been developed. It can be hoped that they will be used…”

Hydrogenated Gold Clusters from Helium Nanodroplets: Cluster Ionization and Affinities for Protons and Hydrogen Molecules

“…The helium beam passed through a 0.8-mm diameter skimmer and entered a pickup region where hydrogen (Messer Austria GmbH, purity 99.999%) was introduced via a needle valve. Gold vapor was produced from solid gold heated with 118 W, which gives a temperature of at least 950 °C, in an oven similar to the one reported by Feng et al [26] that is located another 115 mm downstream. The vapor pressures in the two pickup cells are on the order of 10 −6 mbar.…”

“…Here, we apply a very low temperature technique with which we can encourage both Au atoms to cluster and molecular hydrogen to adsorb on these clusters within a superfluid helium environment provided by helium droplets [22–26]. A beam of nanodroplets of helium is seeded with molecules of hydrogen and atoms of gold and these are allowed to interact before electron impact ionization of the droplets.…”