Single-Molecule Projects

Single-Molecule Spectroscopy, Imaging and Quantum Optics (since 1995)


Cryogenic Correlative Single-Particle Photoluminescence Spectroscopy and Electron Tomography for Investigation of Nanomaterials

Cryogenic single-particle photoluminescence (PL) spectroscopy has been used with great success to directly observe the heterogeneous photophysical states present in a population of luminescent particles. Cryogenic electron tomography provides complementary nanometer scale structural information to PL spectroscopy, but the two techniques have not been correlated due to technical challenges. Here, we present a method for correlating single-particle information from these two powerful microscopy modalities. We simultaneously observe PL brightness, emission spectrum, and in-plane excitation dipole orientation of CdSSe/ZnS quantum dots suspended in vitreous ice. Stable and fluctuating emitters were observed, as well as a surprising splitting of the PL spectrum into two bands with an average energy separation of 80 meV. In some cases, the onset of the splitting corresponded to changes in the in-plane excitation dipole orientation. These dynamics were assigned to structures of individual quantum dots and the excitation dipoles were visualized in the context of structural features.

Peter D. Dahlberg*, Davis Perez*, Zhaoming Su, Wah Chiu, and W. E. Moerner,(*Equal contgributions), "Cryogenic Correlative Single-Particle Photoluminescence Spectroscopy and Electron Tomography for Investigation of Nanomaterials,"  Angew. Chem. Int. Ed. 59, 15642–15648 (2020) (DOI: 10.1002/anie.202002856, published online 11 May 2020). [Slide]


Mostly new fluorophores, crystal and polymer studies, quantum optical experiments. (For biophysical studies, see other links in the left column)

  • Single and Moving Terrylene Molecules in a Spin-Coated Crystal [PDF] [Movies]
  • A Novel Fluorophore for Two-Photon-Excited Single-Molecule Fluorescence: Chem. Phys. 318, 7 (2005)
  • Nonlinear Optical Chromophores for Single-Molecule Spectroscopy [Slide]
  • Novel Reporter Fluorophores for Single-Molecule Imaging [Slides]
  • Single-Molecule Orientational Imaging of Perylenediimide-poly (butadiene) [Slides]
  • Room Temperature Source of Single Photons on Demand [Slide]
  • Photon Antibunching for Single CdSe Quantum Dots [Abstract]
  • Imaging Single Molecules Aligned Both Parallel and Perpendicular to the Optic Axis : Phys. Rev. Lett. 81, 5322 (1998)
  • Pumping Single Molecules with Whispering Gallery Modes of Microspheres [Abstract]