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Vainer YG, Sobolev YI, Naumov AV, Osad'ko IS, Kador L. Fluorescence microscopy and spectroscopy of subsurface layer dynamics of polymers with nanometer resolution in the axial direction. Faraday Discuss 2015; 184:237-49. [DOI: 10.1039/c5fd00055f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We studied the dynamics in ultrathin subsurface layers of an amorphous polymer by the spectra of single fluorescent molecules embedded into the layer by vapor deposition and subsequent controlled diffusion to the desired depth in ≈0.5 nm steps. The spectral trails of single molecules were recorded at 4.5 K as a function of diffusion depth. In depths shallower than 20 nm, the spectral dynamics deviate from those deep in the bulk. Less than 5 nm deep, the linewidths increase rapidly, whereas the number of detected molecules decreases. No zero-phonon lines were observed closer than 0.5 nm to the polymer surface. Possible physical reasons of the observed phenomena are discussed.
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Affiliation(s)
- Yuri G. Vainer
- Institute for Spectroscopy
- Russian Academy of Sciences
- 142190 Moscow
- Russia
- Moscow Institute of Physics and Technology
| | | | - Andrei V. Naumov
- Institute for Spectroscopy
- Russian Academy of Sciences
- 142190 Moscow
- Russia
- Moscow Institute of Physics and Technology
| | - Igor S. Osad'ko
- Institute for Spectroscopy
- Russian Academy of Sciences
- 142190 Moscow
- Russia
| | - Lothar Kador
- University of Bayreuth
- Institute of Physics and BIMF
- 95440 Bayreuth
- Germany
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Tian Y, Navarro P, Kozankiewicz B, Orrit M. Spectral Diffusion of Single Dibenzoterrylene Molecules in 2,3-Dimethylanthracene. Chemphyschem 2012; 13:3510-5. [DOI: 10.1002/cphc.201200463] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Indexed: 11/07/2022]
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Osad'ko IS, Shchukina AL. Blinking fluorescence of single donor-acceptor pairs: important role of "dark'' states in resonance energy transfer via singlet levels. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061907. [PMID: 23005127 DOI: 10.1103/physreve.85.061907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 03/23/2012] [Indexed: 06/01/2023]
Abstract
The influence of triplet levels on Förster resonance energy transfer via singlet levels in donor-acceptor (D-A) pairs is studied. Four types of D-A pair are considered: (i) two-level donor and two-level acceptor, (ii) three-level donor and two-level acceptor, (iii) two-level donor and three-level acceptor, and (iv) three-level donor and three-level acceptor. If singlet-triplet transitions in a three-level acceptor molecule are ineffective, the energy transfer efficiency E=I_{A}/(I_{A}+I_{D}), where I_{D} and I_{A} are the average intensities of donor and acceptor fluorescence, can be described by the simple theoretical equation E(F)=FT_{D}/(1+FT_{D}). Here F is the rate of energy transfer, and T_{D} is the donor fluorescence lifetime. In accordance with the last equation, 100% of the donor electronic energy can be transferred to an acceptor molecule at FT_{D}≫1. However, if singlet-triplet transitions in a three-level acceptor molecule are effective, the energy transfer efficiency is described by another theoretical equation, E(F)=F[over ¯](F)T_{D}/[1+F[over ¯](F)T_{D}]. Here F[over ¯](F) is a function of F depending on singlet-triplet transitions in both donor and acceptor molecules. Expressions for the functions F[over ¯](F) are derived. In this case the energy transfer efficiency will be far from 100% even at FT_{D}≫1. The character of the intensity fluctuations of donor and acceptor fluorescence indicates which of the two equations for E(F) should be used to find the value of the rate F. Therefore, random time instants of photon emission in both donor and acceptor fluorescence are calculated by the Monte Carlo method for all four types of D-A pair. Theoretical expressions for start-stop correlators (waiting time distributions) in donor and acceptor fluorescence are derived. The probabilities w_{N}^{D}(t) and w_{N}^{A}(t) of finding N photons of donor and acceptor fluorescence in the time interval t are calculated for various values of the energy transfer rate F and for all four types of D-A pair. Comparison of the calculated D and A fluorescence trajectories with those measured by Weiss and co-workers proves the important role of triplet levels in energy transfer via singlet levels.
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Affiliation(s)
- I S Osad'ko
- Institute for Spectroscopy, RAS, Troitsk, Russia
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Herascu N, Najafi M, Amunts A, Pieper J, Irrgang KD, Picorel R, Seibert M, Zazubovich V. Parameters of the protein energy landscapes of several light-harvesting complexes probed via spectral hole growth kinetics measurements. J Phys Chem B 2011; 115:2737-47. [PMID: 21391534 DOI: 10.1021/jp108775y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The parameters of barrier distributions on the protein energy landscape in the excited electronic state of the pigment/protein system have been determined by means of spectral hole burning for the lowest-energy pigments of CP43 core antenna complex and CP29 minor antenna complex of spinach Photosystem II (PS II) as well as of trimeric and monomeric LHCII complexes transiently associated with the pea Photosystem I (PS I) pool. All of these complexes exhibit sixty to several hundred times lower spectral hole burning yields as compared with molecular glassy solids previously probed by means of the hole growth kinetics measurements. Therefore, the entities (groups of atoms), which participate in conformational changes in protein, appear to be significantly larger and heavier than those in molecular glasses. No evidence of a small (∼1 cm(-1)) spectral shift tier of the spectral diffusion dynamics has been observed. Therefore, our data most likely reflect the true barrier distributions of the intact protein and not those related to the interface or surrounding host. Possible applications of the barrier distributions as well as the assignments of low-energy states of CP29 and LHCII are discussed in light of the above results.
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Affiliation(s)
- Nicoleta Herascu
- Department of Physics, Concordia University, Montreal, Quebec, Canada
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Krause S, Aramendia PF, Täuber D, von Borczyskowski C. Freezing single molecule dynamics on interfaces and in polymers. Phys Chem Chem Phys 2011; 13:1754-61. [PMID: 21152494 DOI: 10.1039/c0cp01713b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Stefan Krause
- Institute of Physics and nanoMA (Center for nanostructured Materials and Analysis), Chemnitz University of Technology, 09107, Chemnitz, Germany.
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Eremchev IY, Vainer YG, Naumov AV, Kador L. Low-temperature dynamics in amorphous polymers and low-molecular-weight glasses--what is the difference? Phys Chem Chem Phys 2010; 13:1843-8. [PMID: 21183979 DOI: 10.1039/c0cp01690j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Numerous experiments have shown that the low-temperature dynamics of a wide variety of disordered solids is qualitatively universal. However, most of these results were obtained with ensemble-averaging techniques which hide the local parameters of the dynamic processes. We used single-molecule (SM) spectroscopy for direct observation of the dynamic processes in disordered solids with different internal structure and chemical composition. The surprising result is that the dynamics of low-molecular-weight glasses and short-chain polymers does not follow, on a microscopic level, the current concept of low-temperature glass dynamics. An extra contribution to the dynamics was detected causing irreproducible jumps and drifts of the SM spectra on timescales between milliseconds and minutes. In most matrices consisting of small molecules and oligomers, the spectral dynamics was so fast that SM spectra could hardly or not at all be recorded and only irregular fluorescence flares were observed. These results provide new mechanistic insight into the behavior of glasses in general: At low temperatures, the local dynamics of disordered solids is not universal but depends on the structure and chemical composition of the material.
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Affiliation(s)
- Ivan Yu Eremchev
- Molecular Spectroscopy Department, Institute for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow reg., 142190, Russia
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Osad'ko IS. Super-Poissonian statistics of on-off jumps in blinking fluorescence of single molecules. J Chem Phys 2009; 131:185101. [PMID: 19916627 DOI: 10.1063/1.3258272] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Blinking fluorescence of a single guest molecule embedded in a polymer matrix and excited by cw laser light is considered. Such fluorescence exhibits quantum jumps from bright on-intervals to dark off-intervals, i.e., so-called on-->off jumps. A system with one type of on-intervals and with two types of off-intervals is studied. A distribution function w(N)(T) for the number N of on-->off jumps in a time interval T is derived. The distribution function is expressed via a threefold integral of three Poissonian functions, each of which relates to the corresponding exponential process in the quantum dynamics of a fluorescent impurity center. Numerical calculations of the distribution function w(N)(T) for four time intervals T of various durations are carried out. The distribution function w(N)(T) is broader as compared with the Poissonian one and has two maxima, one of which relates to observed time intervals without on-->off jumps.
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Affiliation(s)
- I S Osad'ko
- Lebedev Physical Institute, RAS, Moscow 119991, Russia.
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Nicolet AAL, Bordat P, Hofmann C, Kol'chenko MA, Kozankiewicz B, Brown R, Orrit M. Single Dibenzoterrylene Molecules in an Anthracene Crystal: Main Insertion Sites. Chemphyschem 2007; 8:1929-36. [PMID: 17680586 DOI: 10.1002/cphc.200700340] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We present a spectroscopic study of the properties of the two principal insertion sites (at 785.1 and 794.3 nm) of single dibenzoterrylene molecules in anthracene single crystals at cryogenic temperatures. We measured the temperature dependence of the line width, the orientation of the transition dipole moments, and the Stark effect. We performed molecular dynamics simulations, which show that one dibenzoterrylene molecule preferably replaces three anthracene molecules. From simulated annealing, we derive the molecular conformations in the most stable insertion sites and the orientations of the transition dipole moments. The good agreement between the spectroscopic results and the simulations allows us to propose unambiguous structures for the two principal spectroscopic sites.
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Nicolet AAL, Hofmann C, Kol'chenko MA, Kozankiewicz B, Orrit M. Single Dibenzoterrylene Molecules in an Anthracene Crystal: Spectroscopy and Photophysics. Chemphyschem 2007; 8:1215-20. [PMID: 17492728 DOI: 10.1002/cphc.200700091] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We study single dibenzoterrylene molecules in an anthracene single crystal at 1.4 K in two insertion sites at 785.1 and 794.3 nm. The single-molecule zero-phonon lines are narrow (about 30 MHz), intense (the detected fluorescence rates at saturation reach 100,000 counts s(-1)), and very photostable. The intersystem-crossing yield is extremely low (10(-7) or lower). All of these features are hallmarks of an excellent system for high-resolution spectroscopy and nanoscale probing at cryogenic temperatures.
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Vainer YG, Naumov AV, Bauer M, Kador L. Experimental evidence of the local character of vibrations constituting the Boson peak in amorphous solids. PHYSICAL REVIEW LETTERS 2006; 97:185501. [PMID: 17155551 DOI: 10.1103/physrevlett.97.185501] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Indexed: 05/12/2023]
Abstract
We report the first measurement of the density of states of low-energy vibrational excitations in a disordered solid via single-molecule (SM) spectroscopy. Optical spectra of many single tetra-tert-butylterrylene (TBT) molecules embedded to amorphous polyisobutylene (PIB) as spectral probes were recorded at low temperatures. The T dependences of SM spectral linewidths showed the broad distribution of local frequencies of vibrations under study. The obtained distribution was compared with the "Boson peak" in pure PIB measured in [R. Inoue, J. Chem. Phys. 95, 5332 (1991)] by neutron scattering. We found that embedding of a small amount of TBT into PIB does not influence markedly on the observed vibrational dynamics. These results prove the local character of low-energy vibrational excitations in glasses and the existence of relationship between these excitations and the Boson peak.
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Affiliation(s)
- Yu G Vainer
- Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow Region, 142190, Russia
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Abstract
A proposal for using single molecules as nanoprobes capable of detecting the trajectory of an elementary charge is discussed in detail. Presented numerical simulations prove that this single-molecule technique allows determination of a three-dimensional single-electron displacement within a few seconds with an accuracy better than 0.006 nm. Surprisingly, this significantly exceeds the accuracy with which the probe molecule itself can be localized (given the same measuring time) by means of single-molecule microscopy. It is also shown that the optimal concentration of probe molecules in the vicinity of the electron (i.e. the concentration which provides the best accuracy of the inferred electron displacement) is of the order of 10(-5) m.
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Affiliation(s)
- Taras Plakhotnik
- School of Physical Sciences, University of Queensland, QLD 4072, Australia.
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Lippitz M, Kulzer F, Orrit M. Statistical evaluation of single nano-object fluorescence. Chemphyschem 2006; 6:770-89. [PMID: 15884060 DOI: 10.1002/cphc.200400560] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Single nano-objects display strong fluctuations of their fluorescence signals. These random and irreproducible variations must be subject to statistical analysis to provide microscopic information. We review the main evaluation methods used so far by experimentalists in the field of single-molecule spectroscopy: time traces, correlation functions, distributions of "on" and "off" times, higher-order correlations. We compare their advantages and weaknesses from a theoretical point of view, illustrating our main conclusions with simple numerical simulations. We then review experiments on different types of single nano-objects, the phenomena which are observed and the statistical analyses applied to them.
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Affiliation(s)
- Markus Lippitz
- Molecular Nano-Optics and Spins, Huygens Laboratory, Leiden Institute of Physics (LION), Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
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