Multiphoton Excitation of Molecular Fluorophores and Nonlinear Laser Microscopy

Xu, Chris; Webb, Watt W.

doi:10.1007/0-306-47070-5_11

Cited by 102 publications

(116 citation statements)

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“…In the absence of annihilation mechanisms, the ground state population can be calculated by assuming that all singlets from the previous pulse have decayed. 17 We find:…”

Section: Organic Molecules In the Absence Of Stimulated Emissionmentioning

confidence: 97%

“…In the absence of annihilation mechanisms, the ground state population can be calculated by assuming that all singlets from the previous pulse have decayed. 17 We find:where Δt = 1/f, is the spacing between pulses, f is the repetition rate and τ T is the triplet lifetime.The resulting fluorescence intensity is shown using dashed lines in Fig. 3a for the case φ ISC = 0.01, f = 80 MHz, τ T = 100 µs.…”

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confidence: 95%

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Plasmonic Sinks for the Selective Removal of Long-Lived States

et al. 2011

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The use of plasmonic nanostructures for the removal of unwanted long-lived states is investigated. We show that the total decay rate of such a state can be increased by up to four orders of magnitude, as compared to its intrinsic radiative decay rate, while leaving other neighboring optical transitions unaffected. For the specific case of molecular triplet excited states, we show that the use of a "plasmonic sink" has the potential to reduce photobleaching and ground state depletion by at least two orders of magnitude. We consider, in addition, the impact of such structures on the performance of organic semiconductor lasers and show that, under realistic device conditions, plasmonic sinks have the capacity to increase the achievable laser repetition rate by a factor equal to the triplet decay rate enhancement. We conclude by studying the effect of exciton diffusion on the triplet density in the presence of metallic nanoparticles. KeywordsPlasmons, Sinks, Nanoshells, Purcell Effect, Quenching, Triplets, Organic Lasers, Photobleaching, Non-radiative decay Plasmonic nanoparticles and antennas have demonstrated significant potential for enhancing the luminescence of adjacent emitters. [1][2][3][4][5][6] The mechanisms for enhancement, however, can be varied and the origin of the increased brightness difficult to unravel. For example, the nanostructure can serve to increase the local electric field at the excitation wavelength resulting in an increased excitation rate, 7-9 or equivalently, absorption efficiency of the emitter. In addition, the scattering cross-section of the particle or radiation pattern of the antenna can lead to a higher collection or out-coupling efficiency for the emitted light. 2, 10 Finally, and most importantly for this work, the increased photonic density of states at the emission wavelength can result, via the Purcell effect, in an increased radiative decay rate, Γ R , for the emitter. [1][2][8][9][10] This effect, however, is typically concomitant with an unwanted and stronger increase in the non-radiative decay rate, Γ NR , due to Joule heating of the metal. [9][10] In the usual case where Γ NR >> Γ R , increases in quantum yield, φ F , are only possible for emitters with very low intrinsic yields 0 R NR φ < Γ Γ . 11 In this work, we show that instead of being detrimental, the high non-radiative decay rate typical of emitters in close proximity to plasmonic structures can be exploited to selectively remove unwanted excited states in a number of physical systems.In molecular systems, for example, the build-up of large triplet state populations prevents the efficient excitation of organic molecules with high repetition rates or continuous sources, 12-13 and can be a significant source of photobleaching. 14-17 Indeed,Hale et al. first proposed and demonstrated the possibility of using plasmonic nanoparticles to increase the photostability of organic thin films. 18 In a later section weshow that in that case, the effect fits into the "diffusive regime", which has several advantages, bu...

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“…In the absence of annihilation mechanisms, the ground state population can be calculated by assuming that all singlets from the previous pulse have decayed. 17 We find:…”

Section: Organic Molecules In the Absence Of Stimulated Emissionmentioning

confidence: 97%

mentioning

confidence: 95%

Plasmonic Sinks for the Selective Removal of Long-Lived States

et al. 2011

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“…24,25 Current interest in MPA includes multiphoton spectroscopy and microscopy 26,27 and plasma physics via multiphoton ionization 28 as well as optical limiting applications.…”

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confidence: 99%

Polarization-selective three-photon absorption and subsequent photoluminescence inCsPbBr3single crystal at room temperature

et al. 2016

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We report on highly polarization-selective three-photon absorption (3PA) in a Bridgman-grown single crystal of CsPbBr3 oriented along the (112) direction, which is an inorganic counterpart to emerging organic-inorganic hybrid halide perovskites for solar-cell and optoelectronic applications. The crystal exhibits strong photoluminescence (PL) at room temperature as a direct consequence of 3PA of fundamental radiation. Interestingly, 3PA disappears when the input polarization is parallel to the (-110) direction. This 3PA effect is strongest when orthogonal to (-110) and the corresponding 3PA coefficient was measured to be γ = 0.14 ± 0.03 cm 3 /GW 2 under picosecond-pulse excitation at the fundamental wavelength of λ = 1200 nm. The laser-induced damage threshold was also determined to be about 20 GW/cm 2 at the same wavelength. Based on relative PL intensities upon λ tuning over the entire 3PA range (1100 nm−1700 nm), we determined the nonlinear optical dispersion of the 3PA coefficient for CsPbBr3, which is consistent with a theoretical prediction. Experimentally observed significant polarization dependence of γ was explained by relevant selection rules. The perovskite is potentially important for nonlinear optical applications owing to its highly efficient 3PA-induced PL response with a sharp on/off ratio by active polarization control.

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“…However, in some cases, for example, rhodamine, the first strong two-photon excitation occurs at wavelengths far below the wavelength corresponding to twice the 1S wavelength. Then-graduate student Chris Xu, now Professor Xu at Cornell, carried out the key initial research yielding our first basic set of two-photon fluorophore excitation data and a general understanding of the problem, thus enabling efficient physiological applications (71)(72)(73)(74)(75). Now, apparatus developed by Professor Warren Zipfel allows us to accumulate excitation spectra efficiently, yielding a large collection of data, most of which are yet to be conveniently made generally available (we write guiltily).…”

Section: Fluorophores For Mpm Fluorescent Marker Molecules For Multipmentioning

confidence: 99%

Commentary on the Pleasures of Solving Impossible Problems of Experimental Physiology

Webb

2006

Annu. Rev. Physiol.

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This commentary presents a series of examples of "impossible experimental problems" that we have encountered over the years in addressing various challenging questions in physiology. We aim to show how stimulating the challenges of physiology can be and demonstrate how our naive invocation of methods from disparate fields of science and engineering has led to delightful resolutions of physiological challenges that were utterly new to this intrepid interdisciplinary researcher. SEDUCTION BY SOME IMPOSSIBLE PROBLEMS OF PHYSIOLOGY Chemical Kinetics in Physiology by Fluorescence Correlation SpectroscopyThis innocent materials scientist was dragged into molecular physiology in the late 1960s, when I was presented with the challenge of understanding how the genomes of the recently defined DNA double helix could be separated into individual DNA strands for transcription. Physical biochemist Elliot Elson addressed this question when he joined the Cornell faculty in 1968, before the enabling transcription enzymes were characterized and understood. My relevant perspective then was derived from the excitement of measuring (for the first time) the fascinating phase-phase interface fluctuations near continuous phase transitions of molecular mixtures as well as intraphase fluctuations in 3 He-4 He isotopic mixtures at temperatures down to −272.5• C and in quantum superconductors to test the forthcoming theories of their fluctuations and statistical thermodynamics of their phase transitions (cf. 1-6). By comparison, the biophysical challenges of cellular physiology looked feasible even at sparse biomolecular concentrations (thus displaying my ignorance of the complexity of biochemistry).That naive innocence led us to develop Fluorescence Correlation Spectroscopy (FCS) (7,8) But our invention was temporarily confounded by its instrumentation difficulties and so, after approximately 10 publications, we abandoned FCS for a decade. The faithful had to wait nearly 20 years before adequate infrastructure in computer capability, laser stability, and optical components was developed. It is ironic that our use of other indicators for correlation spectroscopies continued unabated. Now the use of FCS is almost a pleasure, yielding hundreds of research papers per year, which we finally recognized when the annual citations of our own FCS papers exceeded 360 during 2004. We now find FCS to be functional in cells as well as on cell membranes and broadly applicable in a variety of geometries (cf. 9-17).FCS did lead us to recognize early on that the sensitivity of fluorescent markers, which can reach single-molecule sensitivity, provided a universal key to molecular signals in molecular cell physiology. We turned to measurement of molecular mobility on the lipid plus protein membranes of living cell surfaces, a challenge not then understood in the light of Singer and Nicolson's (18) fluid mosaic model and still controversial in the age of the mysterious lipid rafts, but improving, as we shall see. Recently our research has led us back...

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Multiphoton Excitation of Molecular Fluorophores and Nonlinear Laser Microscopy

Cited by 102 publications

References 74 publications

Plasmonic Sinks for the Selective Removal of Long-Lived States

Plasmonic Sinks for the Selective Removal of Long-Lived States

Polarization-selective three-photon absorption and subsequent photoluminescence inCsPbBr3single crystal at room temperature

Commentary on the Pleasures of Solving Impossible Problems of Experimental Physiology

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