Ortho‐Dichlorobenzene Doped with Terrylene—a Highly Photo‐Stable Single‐Molecule System Promising for Photonics Applications

The study of a new dye‐matrix system—quickly frozen ortho‐dichlorobenzene weakly doped with terrylene—via single‐molecule (SM) spectroscopy is presented. The spectral and photo‐physical properties, dynamics, and temperature broadening of SM spectra at low temperatures are discussed. The data reveal a broad inhomogeneous distribution, which indicates a high degree of matrix inhomogeneities, but at the same time, huge fluorescence emission rates and extraordinary SM spectral and photochemical stability with almost complete absence of blinking and bleaching. These unusual properties render the new system a promising candidate for applications in photonics, for example, for delivering single photons on demand.     

Impurity spectroscopy at its ultimate limit: relation between bulk spectrum, inhomogeneous broadening, and local disorder by spectroscopy of (nearly) all individual dopant molecules in solids

We present a technique for the measurement of the low-temperature fluorescence excitation spectra and imaging of a substantial fraction of all single chromophore molecules (hundreds of thousands and even more) embedded in solid bulk samples as nanometre-sized probes. An important feature of our experimental studies is that the full information about the lateral coordinates and spectral parameters of all individual molecules is stored for detailed analysis. This method enables us to study a bulk sample in a broad spectral region with ultimate sensitivity, combining excellent statistical accuracy and the capability of detecting rare events. From the raw data we determined the distributions of several parameters of the chromophore spectra and their variations across the inhomogeneous absorption band, including the frequencies of the electronic zero-phonon lines, their spectral linewidths, and fluorescence count rates. Relationships between these distributions and the disorder of the matrix were established for the examples of two polycrystalline solids with very different properties, n-hexadecane and o-dichlorobenzene, and the amorphous polymer polyisobutylene. We also found spatially inhomogeneous distributions of some parameters.     

Application of the broad hole burning technique for studying low-temperature photoreactions in impurity amorphous bodies

A new experimental method is developed for measuring kinetics of low-temperature photoreactions—the broad hole burning technique, which eliminates the nonexponentiality of the hole burning kinetics caused by the inhomogeneous broadening. The method is successfully used to study the low-temperature photoreactions in various impurity amorphous systems. Examples of single-and two-exponential kinetics have been found, as well as kinetics with a moderate or large dispersion of the hole burning quantum efficiency. The results obtained show a good outlook for the broad hole burning technique for studying low-temperature photoreactions and illustrate the diversity of photoreactions occurring in specific chromophore-matrix pairs.     

Wide-Range Spectral Diffusion in Single Mg-Tetraazaporphyrin Molecules in a Polymer Matrix at Cryogenic Temperatures

Zero-phonon spectral lines of single Mg-tetraazaporphyrin molecules in a polymer matrix and their spectral trails are recorded using cryogenic fluorescence nanoscopy at a temperature of 6 K. Spectral diffusion (stochastic jumps of zero-phonon lines) in an anomalously wide spectral range up to several tens of inverse centimeters is revealed. The structure of the vibronic band in the fluorescence excitation spectrum of single molecules, including both a narrow zero-phonon line and a broad phonon sideband, is directly observed.     

Direct Observation of a Quasilocalized Low-Frequency Vibrational Mode in the Fluorescence Excitation Spectrum of a Single Impurity Molecule in a Polymer Matrix

Optics and Spectroscopy - The possibility of direct observation of a quasi-localized elementary excitation of the phonon type in polyisobutylene has been demonstrated by detecting the fluorescence...