Abstract:The control of light emission on the scale of individual quantum systems, like molecules or quantum dots, is a field of intense current research. One way to induce light emission from these systems is the local charge injection through the tip of a scanning tunnelling microscope (STM). Studies which employ this method have to address one basic question: Does the detected luminescence provide information precisely from the molecule into which charge is injected by the STM tip apex or are the luminescence proper… Show more
“…The main line has been ascribed to a self-trapped exciton. Interestingly, the free singlet exciton with an energy of 1.78 eV is also observed with very low intensity . The free exciton has been interpreted in terms of an excimer state in the literature and has a short lifetime, which may explain the weak intensity in the spectrum.…”
Section: Light Emission By Electron–hole Pair
Recombinationmentioning
confidence: 90%
“…This cross-talk can be avoided by spectral filtering in front of the detectors 97 or by the use of an HBT geometry where the optical paths are long enough to time-separate the flash from the studied correlation. 98 In a start−stop measurement where the start pulse is given by an external trigger, the timer will be stopped by one of the time-resolving detectors. This setup is unaffected by the discussed artifacts and has been employed for the voltage pulse measurements described in section 7.2.…”
Section: Time-resolved Measurementsmentioning
confidence: 99%
“…Interestingly, the free singlet exciton with an energy of 1.78 eV is also observed with very low intensity. 98 The free exciton has been interpreted in terms of an excimer state in the literature 250 and has a short lifetime, which may explain the weak intensity in the spectrum. Free pentacene excitons can stabilize in the self-trapped state (gaining an energy of ΔE = 0.18 eV) or undergo fission into two triplet excitons in a process liberating ΔE = 0.25 eV.…”
Section: Excitons In Single Molecules and Nanostructuresmentioning
confidence: 99%
“…The emitted light travels back through the optical system and can lead to detection of spurious photons in the respective other detector. This cross-talk can be avoided by spectral filtering in front of the detectors or by the use of an HBT geometry where the optical paths are long enough to time-separate the flash from the studied correlation . In a start–stop measurement where the start pulse is given by an external trigger, the timer will be stopped by one of the time-resolving detectors.…”
The conversion of electric power to light is an important scientific and technological challenge. Advanced experimental methods have provided access to explore the relevant microscopic processes at the nanometer scale. Here, we review state-of-the-art studies of electroluminescence induced on the molecular scale by scanning tunneling microscopy. We discuss the generation of excited electronic states and electron-hole pairs (excitons) at molecular interfaces and address interactions between electronic states, local electromagnetic fields (tip-induced plasmons), and molecular vibrations. The combination of electronic and optical spectroscopies with atomic-scale spatial resolution is able to provide a comprehensive picture of energy conversion at the molecular level. A recently developed aspect is the characterization of electroluminescence emitters as quantum light sources, which can be studied with high time resolution, thus providing access to picosecond dynamics at the atomic scale.
“…The main line has been ascribed to a self-trapped exciton. Interestingly, the free singlet exciton with an energy of 1.78 eV is also observed with very low intensity . The free exciton has been interpreted in terms of an excimer state in the literature and has a short lifetime, which may explain the weak intensity in the spectrum.…”
Section: Light Emission By Electron–hole Pair
Recombinationmentioning
confidence: 90%
“…This cross-talk can be avoided by spectral filtering in front of the detectors 97 or by the use of an HBT geometry where the optical paths are long enough to time-separate the flash from the studied correlation. 98 In a start−stop measurement where the start pulse is given by an external trigger, the timer will be stopped by one of the time-resolving detectors. This setup is unaffected by the discussed artifacts and has been employed for the voltage pulse measurements described in section 7.2.…”
Section: Time-resolved Measurementsmentioning
confidence: 99%
“…Interestingly, the free singlet exciton with an energy of 1.78 eV is also observed with very low intensity. 98 The free exciton has been interpreted in terms of an excimer state in the literature 250 and has a short lifetime, which may explain the weak intensity in the spectrum. Free pentacene excitons can stabilize in the self-trapped state (gaining an energy of ΔE = 0.18 eV) or undergo fission into two triplet excitons in a process liberating ΔE = 0.25 eV.…”
Section: Excitons In Single Molecules and Nanostructuresmentioning
confidence: 99%
“…The emitted light travels back through the optical system and can lead to detection of spurious photons in the respective other detector. This cross-talk can be avoided by spectral filtering in front of the detectors or by the use of an HBT geometry where the optical paths are long enough to time-separate the flash from the studied correlation . In a start–stop measurement where the start pulse is given by an external trigger, the timer will be stopped by one of the time-resolving detectors.…”
The conversion of electric power to light is an important scientific and technological challenge. Advanced experimental methods have provided access to explore the relevant microscopic processes at the nanometer scale. Here, we review state-of-the-art studies of electroluminescence induced on the molecular scale by scanning tunneling microscopy. We discuss the generation of excited electronic states and electron-hole pairs (excitons) at molecular interfaces and address interactions between electronic states, local electromagnetic fields (tip-induced plasmons), and molecular vibrations. The combination of electronic and optical spectroscopies with atomic-scale spatial resolution is able to provide a comprehensive picture of energy conversion at the molecular level. A recently developed aspect is the characterization of electroluminescence emitters as quantum light sources, which can be studied with high time resolution, thus providing access to picosecond dynamics at the atomic scale.
“…The achievable experimental time resolution is limited by the time jitter of the photon detector and estimated to be less than 1.1 ns for the APD used here. 22 The only requirement to use the photon intensity as a voltage probe is its strictly monotonic dependence on the applied voltage, since the photon emission is instantaneous on our measurement time scale (see above). Once known, this dependence can be used to convert the photon intensity back to an instantaneous transient voltage in the junction.…”
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