Influence of band structure on ballistic transport revealed by molecular nanoprobe

Electron-Induced Switching Processes of Phthalocyanine Molecules on (3×3) Bi/Ag(111)R30°: Tautomerization Accompanied by Rotation

“…The symmetric behavior around the Fermi energy corroborates the assumption that both processes are triggered by inelastic electron tunneling. ,, A strong gradient in the electron yield indicates the opening of an additional inelastic tunneling channel, possibly related to the onset of a vibrational mode. , If the energy of the vibrational mode is sufficiently high, tunneling through or lifting above the potential barrier eventually triggers the molecule’s rotation or tautomerization. ,, In order to extract possible vibrational modes, the graphs in Figure a,b were analyzed quantitatively by a spectral fitting method. , The resulting energy onsets are summarized in Table . Negative and positive thresholds are in accordance with the first and second harmonic of the N–H stretching mode, an observation which agrees well with previous results for tautomerization of phthalocyanine on the Ag(111) as well as the Cu(111) surface. , Therefore, we conclude that both processes, tautomerization and rotation, are triggered by the N–H stretching mode.…”

“…Negative and positive thresholds are in accordance with the first and second harmonic of the N−H stretching mode, an observation which agrees well with previous results for tautomerization of phthalocyanine on the Ag(111) as well as the Cu(111) surface. 43,47 Therefore, we conclude that both processes, tautomerization and rotation, are triggered by the N−H stretching mode.…”

Real-space resolved surface reactions: deprotonation and metalation of phthalocyanine

“…In contrast, charge carriers from bulk states (black filled region) cannot contribute to the measured electron yield in MONA. Since on-top and remote excitation qualitatively agree even below the onset of the surface state, which is in strong contrast to previous measurements on Ag(111) 30 and Cu(111), 20 we can safely conclude that in both cases the resonant tunneling of charge carriers from the blue marked energy window into MOs dominates the electron yield.…”

“…The tautomerization of HPc on Cu(111) has been reported recently in a detailed study by us. 20 With a second voltage pulse above U E 2.5 V, the remaining hydrogen atom can also be removed, resulting in H 0 Pc which remains stable up to bias voltages U = AE3.0 V. In agreement with previous reports, 21 we conclude that the type 2 molecules are H 0 Pc which result from a substrateinduced deprotonation of H 2 Pc (type 1) upon adsorption. As we will discuss later in this contribution, type 3 molecules are the product of a surface-induced metalation to CuPc.…”

“…On the other hand, the path of the charge carriers is strikingly different: While, for on-top measurements, charge carriers tunnel through the molecule, we have demonstrated in a recent publication that for MONA measurements they dominantly propagate within the surface state of Cu(111) towards the molecule. 20 At the molecule, they eventually scatter inelastically or migrate to a molecular state which has a significant overlap with the surface. Considering the sketch in the bottom left of Fig.…”