Papers by Nikolay Makarov
Dispersion of the Third-Order Nonlinear Optical Response of Organics Using a Few State Model
Conference on Lasers and Electro-Optics 2012, 2012
ABSTRACT Dispersion of the third-order nonlinear optical response can be predicted using a pertur... more ABSTRACT Dispersion of the third-order nonlinear optical response can be predicted using a perturbative few-state model approach with knowledge of the linear and two-photon absorption spectra. This approach has been applied toward polymethines and squaraines.
Correlating one-photon, two-photon and excited state spectroscopy of CdSe quantum dots
2012 Conference on Lasers and Electro Optics, 2012
ABSTRACT We present two-photon absorption and excited-state absorption spectra of quantum dots. F... more ABSTRACT We present two-photon absorption and excited-state absorption spectra of quantum dots. From the linear and transient spectra we determine transition dipole moments between the states and compare them with the two-photon cross-sections.
Two-photon absorption standards in the 550-1600 nm excitation range: establishing a correction curve for accurate cross section calibration
Proceedings of Spie the International Society For Optical Engineering, 2008
We present absolute two-photon absorption (2PA) spectra of 15 commercial organic dyes covering an... more We present absolute two-photon absorption (2PA) spectra of 15 commercial organic dyes covering an extended range of excitation wavelengths, 550-1600 nm. The 2PA is measured with an estimated accuracy +/-10% using a femtosecond fluorescence excitation method. The data are corrected for the variations of the pulse duration and the beam profile with the excitation wavelength, and are applicable as reference standards for 2PA measurements.
Origin of Different Color Hues in Fluorescent Proteins with the Same Chromophore 1 ALEKSANDER REB... more Origin of Different Color Hues in Fluorescent Proteins with the Same Chromophore 1 ALEKSANDER REBANE, MIKHAIL DROBIZHEV, SHANE TILLO, NIKOLAY MAKAROV, THOMAS HUGHES, Montana State University -Fluorescent proteins (FPs) exhibit broad varietyof absorption and emission colors even though some mutants share the same chromophore structure. We demonstrate that in red FPs including DsRed, mRFP, and mFruits (absorption peak 540 to 590 nm), as well as in green FPs including EGFP, TagGFP, mWasabi, GX variants, and mTFP variants (absorption peak 450 to 500 nm) the colors are caused by internal Stark effect. We use quantitative two-photon absorption spectroscopy to show that the colors changes can be explained by quadratic Stark shifts due to variations of the strong local electric field within the beta barrel. This allows us, for the first time tour knowledge, to directly measure the internal electric field inside a protein. The obtained maximum values up to 10 to 100 MV/cm in the mFruits series are rather large, however, these field strengths are still 1 -2 orders less than those required to ionize the chromophore. These measured values also correspond well with previous theoretical estimates for different proteins. Our finding suggests a new way to sense electrical fields in biological systems, while it also bring order to a bewildering diversity of FP properties 1 NIH NIGMS grant 1 R01 GM086198-01.
Fluorescence In Vivo Imaging Based on Genetically Engineered Probes: From Living Cells to Whole Body Imaging IV
... A noncytotoxic DsRed variant for whole-cell labeling. Author(s): Rita L. Strack; Daniel E. St... more ... A noncytotoxic DsRed variant for whole-cell labeling. Author(s): Rita L. Strack; Daniel E. Strongin; Dibyendu Bhattacharyya; Wen Tao; Allison Berman; Hal E. Broxmeyer; Robert J. Keenan MD; Benjamin S. Glick. Quantitative ...
Room Temperature Single-Photon Emission from Individual Perovskite Quantum Dots
ACS nano, Jan 27, 2015
Lead-halide-based perovskites have been the subject of numerous recent studies largely motivated ... more Lead-halide-based perovskites have been the subject of numerous recent studies largely motivated by their exceptional performance in solar cells. Electronic and optical properties of these materials have been commonly controlled by varying the composition (e.g., the halide component) and/or crystal structure. Use of nanostructured forms of perovskites can provide additional means for tailoring their functionalities via effects of quantum confinement and wave function engineering. Furthermore, it may enable applications that explicitly rely on the quantum nature of electronic excitations. Here, we demonstrate that CsPbX3 quantum dots (X = I, Br) can serve as room-temperature sources of quantum light, as indicated by strong photon antibunching detected in single-dot photoluminescence measurements. We explain this observation by the presence of fast nonradiative Auger recombination, which renders multiexciton states virtually nonemissive and limits the fraction of photon coincidence ev...
Experimental characterization of two-photon materials for fast rewritable optical data storage
Proceedings of SPIE - The International Society for Optical Engineering
ABSTRACT
We describe an experimental setup for reliable relative measurements of two-photon absorption spe... more We describe an experimental setup for reliable relative measurements of two-photon absorption spectra of organic molecules. The set-up utilizes tunable femtosecond laser system with optical parametric amplifier (OPA) and covers excitation wavelengths in the range 550-1600 nm. It utilizes two channels for simultaneous measurements of the unknown sample and the reference, such that all the pulse-to-pulse laser instabilities cancel out during measurements. Using the setup we measure absolute two-photon absorption (2PA) spectra of 4 commercial organic dyes (Rhodamine 640, Rhodamine 700, LDS-698 and LDS-798) with an estimated accuracy 15%. The data are corrected for the variations of the pulse duration and the beam profile with the excitation wavelength, and are applicable as secondary reference standards for 2PA measurements of the compounds with the emission wavelengths 600-800 nm.
Nature nanotechnology, Jan 24, 2015
Luminescent solar concentrators serving as semitransparent photovoltaic windows could become an i... more Luminescent solar concentrators serving as semitransparent photovoltaic windows could become an important element in net zero energy consumption buildings of the future. Colloidal quantum dots are promising materials for luminescent solar concentrators as they can be engineered to provide the large Stokes shift necessary for suppressing reabsorption losses in large-area devices. Existing Stokes-shift-engineered quantum dots allow for only partial coverage of the solar spectrum, which limits their light-harvesting ability and leads to colouring of the luminescent solar concentrators, complicating their use in architecture. Here, we use quantum dots of ternary I-III-VI2 semiconductors to realize the first large-area quantum dot-luminescent solar concentrators free of toxic elements, with reduced reabsorption and extended coverage of the solar spectrum. By incorporating CuInSexS2-x quantum dots into photo-polymerized poly(lauryl methacrylate), we obtain freestanding, colourless slabs t...
<title>Phthalocyanine molecules with extremely strong two-photon absorption for 3D rewritable optical information storage</title>
Photonics for Space Environments XI, 2006
Phthalocyanines (Pcs) show exceptional stability against high temperatures (up to 900°C, for cert... more Phthalocyanines (Pcs) show exceptional stability against high temperatures (up to 900°C, for certain metallophthalocyanines), harsh chemical environments (strong acids and bases), gamma-radiation (up to 100 MRad) and neutron radiation (up to 1019 thermal neutrons/cm2). On the other hand, Pcs exhibit a number of unique physical properties, including semi-conductivity, photoconductivity, large linear and nonlinear optical coefficients, and the ability of photo-switch between two different forms, in case of non-symmetrical metal-free Pcs. This has led to an advancement of phthalocyanine-based prototype field-effect transistors, gas- and photo-sensors, solar cells, optical power limiters, and optical memory devices (CDs). For increasing the capacity of carriers of information, it has been suggested to use the effect of simultaneous two-photon absorption (2PA), which can allow for writing and reading information in many layers, thus resulting in Terabyte (TB) disks. Our estimation of the signal-to-noise ratio shows, however, that for fast (MB/s) processing, molecular 2PA cross section must be extremely large, sigma2 > 103 - 104 GM (1GM = 10-50 cm4 s), which has not been achieved yet in any photochromic material. In this paper we demonstrate, for the first time, that some specially designed non-symmetric metal-free phthahlocyanines are almost ideally suited for TB rewritable memory due to their extremely high, resonantly enhanced, 2PA cross section (~ 104 GM) in near-IR region and their intrinsic ability of reversible photo-tautomerization at lowered (~ 100 K) temperatures. We discuss how the special technical specifications, such as short pulse laser excitation and lowered working temperature, can be satisfied for space and terrestrial application.
Tuning the Redox Coupling between Quantum Dots and Dopamine in Hybrid Nanoscale Assemblies
The Journal of Physical Chemistry C, 2015
ABSTRACT We explored the charge transfer interactions between CdSe-ZnS core-shell quantum dots (Q... more ABSTRACT We explored the charge transfer interactions between CdSe-ZnS core-shell quantum dots (QDs) and the redox active neurotransmitter dopamine, using covalently assembled QD-dopamine conjugates. We combined steady-state fluorescence, time-resolved fluorescence, and transient absorption bleach measurements to probe the effects of changing the QD size (thus the QD energy levels) and the conjugate valence on the rate of QD photoluminescence quenching when the pH of the medium was adjusted from acidic to alkaline. We measured substantially larger quenching efficiencies, combined with more pronounced shortening of the carrier dynamics of these assemblies for smaller size QDs and in alkaline pH. Moreover, we found that changes in the QD size alter the electron and hole relaxation of photoexcited QDs but with different extents. For instance, a pronounced change in the hole relaxation was measured in alkaline buffers. Moreover, the hole relaxation was faster for conjugates of green-emitting QDs as compared to their red-emitting counterparts. We attribute these results to the more favorable electron transfer rates from the reduced form of the dopamine to the valence band of the QDs, a process that becomes more efficient for green-emitting QDs. The latter benefits from lower oxidation potential and larger energy mismatch with the green QDs in alkaline buffers. In comparison, the effects of pH changes on the rates of electron transfer from excited QDs to dopamine are less affected by the QD size. These findings reflect the importance of the energy mismatch between the QD energy levels and the redox levels of dopamine, and shed light onto the complex interactions involved in these assemblies. Such conjugates also provide promising sensing and imaging tools for use in in vivo experiments.
J. Mater. Chem. C, 2014
S1.1 Instruments 1 H and 13 C NMR spectroscopies were conducted with a Varian Mercury300 spectrom... more S1.1 Instruments 1 H and 13 C NMR spectroscopies were conducted with a Varian Mercury300 spectrometer using tetramethylsilane (TMS; δ=0 ppm) as an internal standard. Elemental analysis was performed by Vario EL III (German). UV-visible spectra were obtained using a Schimadzu UV-2550 spectrometer. Cyclic voltammetry (CV) was carried out on a CHI voltammetric analyzer in a three-electrode cell with a Pt counter electrode, a Ag/AgCl reference electrode, and a glassy carbon working electrode at a scan rate of 10mV/s. The potential values obtained were converted to values versus the ferrocenium/ferrocene (Fc + /Fc) standard. All chemicals are commercially available and were used as received. Scheme S1 Synthesis route for compound 2
Narrowing of the homogeneous two-photon absorption line width in two-level dipolar system
SPIE Proceedings, 2008
ABSTRACT
<title>Maximizing two-photon absorption cross section within few essential state model</title>
Organic Photonic Materials and Devices XII, 2010
ABSTRACT
Environment-sensitive two-photon dye
Linear and Nonlinear Optics of Organic Materials VIII, 2008
ABSTRACT We present a detailed study of the local environmental sensitivity of the commercially a... more ABSTRACT We present a detailed study of the local environmental sensitivity of the commercially available laser dye, Styryl-9M. Positions of the one-photon and two-photon absorption maxima and two-photon absorption minimum of the dye are sensitive to the solvent polarity. In aqueous solution its absorption and fluorescence spectra consist of two peaks whose relative strength depend on the surrounding pH-s. The dye shows one of the highest two-photon absorption cross sections, 700-1300 GM at the peak, among widely available compounds. Comparison of the linear and nonlinear properties shows that its maximum cross section can be described by an effective two-level model. Based on the properties of Styryl-9M we propose a new method of sensing local environment polarity in solutions and biological phantoms. We show that the dye is a promising candidate for two-photon biological imaging and microscopy.
<title>Two-photon absorption spectroscopy of corroles</title>
Organic Photonic Materials and Devices XI, 2009
We report simultaneous two-photon absorption (2PA) spectra in a series of substituted corroles an... more We report simultaneous two-photon absorption (2PA) spectra in a series of substituted corroles and related porphyrins in 800-1400 nm laser wavelength range. Compared to the porphyrins, the 2PA spectrum of corroles contains a distinct and relatively high intensity peak, sigma(2) = 60-130 GM, close to twice the wavelength of Soret maximum (800-850 nm). The increase of 2PA peak cross section
Broad bandwidth near-IR two-photon absorption in conjugated porphyrin-core dendrimers
SPIE Proceedings, 2007
ABSTRACT
Optical Materials Express, 2011
We present a methodology for rapidly acquiring broadband twophoton absorption (2PA) spectra by me... more We present a methodology for rapidly acquiring broadband twophoton absorption (2PA) spectra by means of a compact two-channel femtosecond fluorescence excitation apparatus. This technique is insensitive to differences in excitation and collection geometries as well as detection efficiencies between the sample and reference, in addition to variations in average power, pulse duration and spatial beam profile, as it utilizes sequential measurement of the sample and reference in each of the two cell positions. Our approach eliminates the need to determine the fluorescence quantum yields of the sample and reference, as it allows measurement of emission from samples at a common specified wavelength. These attributes allow for acquisition of 2PA spectra with an estimated accuracy of ± 15% (limited almost exclusively by the uncertainty in the 2PA cross section for the reference standards) over an excitation range of 550-1600 nanometers with a typical time per spectrum of ~30-60 minutes. We have applied this technique to determine the 2PA spectra of six commercially available organic dyes over a wide range of excitation wavelengths (670-1600 nm), which can be used as secondary reference standards emitting in the red and near-infrared spectral region (600-1000 nm). We have also characterized some of these compounds using the femtosecond-pulsed Z-scan method and found very good agreement with the fluorescence-based measurements.
Nature Communications, 2014
One process limiting the performance of solar cells is rapid cooling (thermalization) of hot carr... more One process limiting the performance of solar cells is rapid cooling (thermalization) of hot carriers generated by higher-energy solar photons. In principle, the thermalization losses can be reduced by converting the kinetic energy of energetic carriers into additional electron-hole pairs via carrier multiplication (CM). While being inefficient in bulk semiconductors this process is enhanced in quantum dots, although not sufficiently high to considerably boost the power output of practical devices. Here we demonstrate that thick-shell PbSe/CdSe nanostructures can show almost a fourfold increase in the CM yield over conventional PbSe quantum dots, accompanied by a considerable reduction of the CM threshold. These structures enhance a valence-band CM channel due to effective capture of energetic holes into long-lived shell-localized states. The attainment of the regime of slowed cooling responsible for CM enhancement is indicated by the development of shell-related emission in the visible observed simultaneously with infrared emission from the core.
Design and Synthesis of Heterostructured Quantum Dots with Dual Emission in the Visible and Infrared
ACS Nano, 2015
The unique optical properties exhibited by visible emitting core/shell quantum dots with especial... more The unique optical properties exhibited by visible emitting core/shell quantum dots with especially thick shells are the focus of widespread study, but have yet to be realized in infrared (IR)-active nanostructures. We apply an effective-mass model to identify PbSe/CdSe core/shell quantum dots as a promising system for achieving this goal. We then synthesize colloidal PbSe/CdSe quantum dots with shell thicknesses of up to 4 nm that exhibit unusually slow hole intraband relaxation from shell to core states, as evidenced by the emergence of dual emission, i.e., IR photoluminescence from the PbSe core observed simultaneously with visible emission from the CdSe shell. In addition to the large shell thickness, the development of slowed intraband relaxation is facilitated by the existence of a sharp core-shell interface without discernible alloying. Growth of thick shells without interfacial alloying or incidental formation of homogeneous CdSe nanocrystals was accomplished using insights attained via a systematic study of the dynamics of the cation-exchange synthesis of both PbSe/CdSe and the related system PbS/CdS. Finally, we show that the efficiency of the visible photoluminescence can be greatly enhanced by inorganic passivation.
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Papers by Nikolay Makarov