Electronic Ground-State and Orbital Ordering of Iron Phthalocyanine on H/Si(111) Unraveled by Spatially Resolved Tunneling Spectroscopy

Abstract

The electronic properties of FePc molecules adsorbed on hydrogen-passivated Si(111) surfaces are investigated by scanning tunneling microscopy at low temperatures. Spatially resolved spectroscopy reveals a significant variation of the electronic states at different positions above the molecule. The highest occupied ligand- and metal-based orbitals of FePc are determined by pronounced peaks in the tunneling spectra and voltage-dependent changes in the microscopic images. Comparison with density functional theory calculations indicates that the electronic ground state is an 3A1g state.

An Isolated Molecule of Iron(II) Phthalocyanin Exhibits Quintet Ground‐State: A Nexus between Theory and Experiment

“…As in other metal‐containing porphyrin‐like molecules, difficulties to properly assign the ground‐state structure result mainly from a near‐degeneracy of d‐orbitals, which often requires multi‐reference treatment. Experimental studies performed by means of the magnetic susceptibility measurements and Mössbauer experiments, circular dichroism, X‐ray spectroscopy, photoelectron spectroscopy, NMR spectroscopy, scanning tunneling microscope (STM) and inelastic electron tunneling spectroscopies assigned the triplet ground‐state of FePc. This supports also agreement of Fe−N distances calculated in our study with the X‐ray spectroscopy (see Figure a).…”

“…This supports also agreement of Fe−N distances calculated in our study with the X‐ray spectroscopy (see Figure a). Guiding by predictions of the experimentally obtained ground state multiplicity, all computational studies on the character of the FePc electronic structure performed with single‐ and multi‐reference methods assumed the triplet only without consideration of other possible multiplicities.…”

“…ing porphyrin-like molecules, difficulties to properly assign the ground-state structure result mainly from an ear-degeneracy of d-orbitals,w hich often requires multi-reference treatment. Experimental studies performed by means of the magnetic susceptibility measurements and Mçssbauer experiments, [26][27][28] circular dichroism, [29,30] X-ray spectroscopy, [31][32][33] photoelectron spectroscopy, [34] NMR spectroscopy, [35] scanningt unneling microscope (STM) [36,37] and inelastic electron tunneling spectroscopies assignedt he triplet ground-stateo fF ePc.T his supports also agreement of FeÀNd istances calculated in our study with the X-ray spectroscopy [32] (see Figure 1a). Guidingb yp redictions of the experimentally obtained ground state multiplicity, all computational studies on the character of the FePc electronic structure performedw ith single- [14,33,34,[36][37][38][39][40][41][42][43][44][45][46] and multireference methods [47] assumed the triplet only without consideration of other possible multiplicities.…”

Characterization of PTCDA nanocrystals on Ge(001):H-(2×1) surfaces

“…For example, in case of metal surfaces such a scenario is realized by means of few monolayers of insulator, like NaCl [5][6][7][8][9][10][11][12][13], for semiconductor surfaces it might be either few monolayers of insulator, like KBr on InSb [14,15], or a single layer of atomic hydrogen, e.g. Si:H and Ge:H surfaces [16][17][18][19][20]. The buffer layer dramatically enhances mobility of adsorbed molecular species and eventually may ease their selfassembly and formation of molecular nanocrystals [9][10][11]20,21].…”

Realization of a quantum Hamiltonian Boolean logic gate on the Si(001):H surface

“…3 Experiments on single organic molecule(s) in prototypical electronic devices became feasible after the invention of the scanning tunnelling microscope (STM), 4,5 enabling structural and electronic characterization as well as the atomically precise construction of atomic and molecular devices. [13][14][15][16] For example, hydrogen passivated silicon 13 and germanium 15 surfaces provide an efficient isolation of adsorbed molecules and preserve their intrinsic electronic properties. 10 However, most of these experiments were conducted on a metal surface.…”