Abstract:The
ability to control the emission from single-molecule quantum
emitters is an important step toward their implementation in optoelectronic
technology. Phthalocyanine and derived metal complexes on thin insulating
layers studied by scanning tunneling microscope-induced luminescence
(STML) offer an excellent playground for tuning their excitonic and
electronic states by Coulomb interaction and to showcase their high
environmental sensitivity. Copper phthalocyanine (CuPc) has an open-shell
electronic structure,… Show more
“…To this end, molecular motion can be induced by a variety of physical and chemical stimuli, depending on the desired functionality 3 . While non-local stimuli, such as an external light source, can address many molecular machines simultaneously [4][5][6] , it is ultimately desirable to create molecular devices where molecules can be addressed individually [7][8][9][10][11] . Controlled on-surface manipulation of single atoms and molecules has been successfully demonstrated using the scanning tunneling microscope (STM), typically via electronic or inelastic (vibrational or vibronic) excitation mechanisms [8][9][10][12][13][14][15][16][17][18] .…”
We demonstrate that nanocavity plasmons generated a few nanometers away from a molecule can induce molecular motion. For this, we study the well-known rapid shuttling motion of zinc phthalocyanine molecules adsorbed on ultrathin NaCl films by combining scanning tunneling microscopy (STM) and spectroscopy (STS) with STM-induced light emission. Comparing spatially resolved single-molecule luminescence spectra from molecules anchored to a step edge with isolated molecules adsorbed on the free surface, we found that the azimuthal modulation of the Lamb shift is diminished in case of the latter. This is evidence that the rapid shuttling motion is remotely induced by plasmon-exciton coupling. Plasmoninduced molecular motion may open an interesting playground to bridge the nanoscopic and mesoscopic worlds by combining molecular machines with nanoplasmonics to control directed motion of single molecules without the need for local probes.
“…To this end, molecular motion can be induced by a variety of physical and chemical stimuli, depending on the desired functionality 3 . While non-local stimuli, such as an external light source, can address many molecular machines simultaneously [4][5][6] , it is ultimately desirable to create molecular devices where molecules can be addressed individually [7][8][9][10][11] . Controlled on-surface manipulation of single atoms and molecules has been successfully demonstrated using the scanning tunneling microscope (STM), typically via electronic or inelastic (vibrational or vibronic) excitation mechanisms [8][9][10][12][13][14][15][16][17][18] .…”
We demonstrate that nanocavity plasmons generated a few nanometers away from a molecule can induce molecular motion. For this, we study the well-known rapid shuttling motion of zinc phthalocyanine molecules adsorbed on ultrathin NaCl films by combining scanning tunneling microscopy (STM) and spectroscopy (STS) with STM-induced light emission. Comparing spatially resolved single-molecule luminescence spectra from molecules anchored to a step edge with isolated molecules adsorbed on the free surface, we found that the azimuthal modulation of the Lamb shift is diminished in case of the latter. This is evidence that the rapid shuttling motion is remotely induced by plasmon-exciton coupling. Plasmoninduced molecular motion may open an interesting playground to bridge the nanoscopic and mesoscopic worlds by combining molecular machines with nanoplasmonics to control directed motion of single molecules without the need for local probes.
“…3 c shows that it can only be excited at positive voltage ( V = 2.5 eV) with an emission line at ≈1.88 eV. Similar to metal phthalocyanines 37 , 40 , 43 , 44 , only a single emission line is observed in this spectrum, reflecting the D4h symmetry of the doubly deprotonated molecule and the associated degeneracy of the two first emission contributions. Fig.…”
Section: Resultsmentioning
confidence: 81%
“…3 . Similarly, we theoretically ruled out the impact of the static screening of the NaCl substrate on the energy shifts by performing DFT and TD-DFT calculations 44 (discussed in detail in Supplementary Note 2 ). On the other hand, charged chromophores as π -type phthalocyanine anions and cations discussed in previous reports 21 – 23 , 49 are systematically characterized by a strongly red-shifted emission (≈400 meV) compared to neutral compounds, reflecting important modifications of the π -orbitals involved in the optical transition.…”
The optical properties of chromophores can be efficiently tuned by electrostatic fields generated in their close environment, a phenomenon that plays a central role for the optimization of complex functions within living organisms where it is known as internal Stark effect (ISE). Here, we realised an ISE experiment at the lowest possible scale, by monitoring the Stark shift generated by charges confined within a single chromophore on its emission energy. To this end, a scanning tunneling microscope (STM) functioning at cryogenic temperatures is used to sequentially remove the two central protons of a free-base phthalocyanine chromophore deposited on a NaCl-covered Ag(111) surface. STM-induced fluorescence measurements reveal spectral shifts that are associated to the electrostatic field generated by the internal charges remaining in the chromophores upon deprotonation.
“…3(c) shows that it can only be excited at positive voltage (V = 2.5 eV) with an emission line at ≈ 1.88 eV. Similarly to metal phthalocyanines, 37,40,43,44 only a single emission line is observed in this spectrum, reflecting the D4h symmetry of the doubly deprotonated molecule and the associated degeneracy of the two first emission contributions.…”
mentioning
confidence: 89%
“…3. Similarly, we theoretically ruled out the impact of the static screening of the NaCl substrate on the energy shifts by performing DFT and TD-DFT calculations 44 (discussed in detail in Supplementary Note 2). On the other hand, charged chromophores as π-type phthalocyanine anions and cations discussed in previous reports [21][22][23]47 are systematically characterized by a strongly red-shifted emission (≈ 400 meV) compared to neutral compounds, reflecting important modifications of the π-orbitals involved in the optical transition.…”
The optical properties of chromophores can be efficiently tuned by electrostatic fields generated in their close environment, a phenomenon that plays a central role for the optimization of complex functions within living organisms where it is known as internal Stark effect (ISE). Here, we realised an ISE experiment at the lowest possible scale, by monitoring the Stark shift generated by charges confined within a single chromophore on its emission energy. To this end, a scanning tunneling microscope (STM) functioning at cryogenic temperatures is used to sequentially remove the two central protons of a free-base phthalocyanine chromophore deposited on a NaCl-covered Ag(111) surface. STM-induced fluorescence measurements reveal spectral shifts that are associated to the electrostatic field generated by the internal charges remaining in the chromophores upon deprotonation.
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