Transient excited singlet state absorption in Rhodamine 6G

Venkateswarlu, Putcha; George, M. C.; Rao, Y.V. Chalapati; Jagannath, H.; Chakrapani, G.; Miahnahri, A.

doi:10.1007/bf02846809

Cited by 25 publications

(13 citation statements)

References 12 publications

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“…The emission and excitation spectra of the R6G:PMMA film on glass, n = 5.2 × 10 20 cm −3 , are depicted in Figure c. In line with the literature, they are asymmetrical and appear to be mirror images of each other. When the same highly doped R6G:PMMA film was placed inside the 140 nm cavity that was resonant with the R6G emission band: (i) the excitation and the emission spectral bands became more symmetrical (Figure c) and (ii) the excitation (emission) band shifted to the shorter (longer) wavelengths, thus increasing the molecule's Stokes shift.…”

Section: Resultsmentioning

confidence: 99%

“…This gives rise to two absorption transitions, |1〉 → |2 P + 〉 and |1〉 → |2 P − 〉, and two emission transitions, |3 P + 〉 → |4〉 and |3 P − 〉 → |4〉. Assuming that the energy separation between the hybrid states | P + 〉 and | P − 〉 is not too large, depopulation of the state |3 P + 〉 is dominated by the nonradiative decay |3 P + 〉 → |3 P − 〉, and the quantum yield of the |3 P + 〉 → |4〉 emission is small . Therefore, only one emission transition, |3 P − 〉 → |4〉 (Figure d), which is red shifted in comparison with the |3〉 → |4〉 transition in uncoupled molecules (Figure c), remains possible.…”

Section: Discussionmentioning

confidence: 99%

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Control of the Stokes Shift with Strong Coupling

Tanyi

Thuman

Brown

et al. 2017

Advanced Optical Materials

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A stronger coupling can be achieved if a molecule is placed into a small resonant Fabry-Perot cavity or to a vicinity of a nanostructure supporting surface plasmon (SP) resonance. The time evolution of the two coupled oscillators, e.g., a cavity and a molecule, can be described as a linear superposition of their normal hybrid modes. [4] The even (odd) oscillation mode has the higher (lower) frequency, ω ± = ω 0 ± Δ, and corresponds to the upper (lower) branch of the dispersion curve. (Here Δ is the coupling frequency and the frequencies of uncoupled oscillators ω 0 are assumed to be the same.) If Δ exceeds all relaxation rates in the system, the dispersion curve features the avoided crossing and the well-resolved energy gap known as the normal mode splitting or the Rabi splitting [4,5] (Figure 1a,b). This criterion does not require the coupling to be large, [3,4] e.g., ≈5 meV, [6] as long as all relaxation processes of importance are sufficiently slow. This is often the case of single quantum emitters coupled to cavities. [7,8] We also propose in Figure 1c,d a model to explain this splitting behavior, which shall be discussed in detail shortly.On the other hand, as the splitting energy 2Δ is getting comparable to ω 0 , one enters the so-called ultrastrong coupling regime. [9] This is the case of large ensembles of dye molecules coupled to plasmonic nanostructures and resonant cavities, which routinely leads to the normal mode splitting (proportional to the square root of the molecular number density / N V ) [4] of the order of 1 eV. [10] Such a large change in the eigenvalues of the hybrid modes paves the way to unprecedented control of electrical conductivity, [11] excitation transport, [12] surface potential, [13] and rates of chemical reactions. [9] Early research of the strong coupling was focused on quantum wells in resonant Bragg cavities. [5] In more recent years, this phenomenon has been studied at low and high (room) temperatures in multiple quantum and classical systems, including quantum dots, [7] single molecules, [8] and large molecular ensembles [14,15] interacting with localized and propagating SPs, [15,16] and cavities. [8,9,17] In spite of large-scale theoretical and experimental efforts, some fundamental aspects of the strong coupling remain to be unexplored. One of them is the debated applicability of the quantum mechanical model to large ensembles of molecules, which may be possible if the latter act as one "giant atom," [4] providing for coherent spontaneous emission, [18,19] and energy oscillations. [20] This fundamental question and the intriguing Strong coupling of excitons in macroscopic ensembles of quantum emitters and cavities (or surface plasmons) can lead to dramatic change of the optical properties and modification of the dispersion curves, characterized by the normal mode splitting of the order of 1 eV. Such gigantic alteration of the hybrid energy states enables scores of unparalleled physical phenomena and functionalities, ranging from enhancement of electrical conductivity to co...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Control of the Stokes Shift with Strong Coupling

Tanyi

Thuman

Brown

et al. 2017

Advanced Optical Materials

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“…At the high molecular concentration used in our experiments (2.69 × 10 20 cm −3 in solid state), rhodamine 6G has (i) a strong absorption band ( λ ≈536 nm) and a shoulder ( λ ≈506 nm) attributed to the electronic singlet–singlet (S 0 →S 1 ) and vibronic transitions, respectively; (ii) a weaker absorption maximum at λ ≈345 nm (S 0 →S 2 transition); and (iii) multiple absorption bands at shorter wavelengths . The positions of the S 0 →S 1 and S 0 →S 2 absorption transitions are indicated in Figure b and d with dashed lines.…”

Section: Cavity Designmentioning

confidence: 87%

Coupling of the First and Second Excited States of R6G Dye with the Fabry–Perot Cavity

Tanyi

Harrison

et al. 2018

Physica Status Solidi (b)

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Coupling of macroscopic ensembles of highly concentrated R6G molecules with aluminum and silver Fabry–Perot cavities of different sizes, in which one or two standing wave modes are in resonance with the absorption transition(s) of the dye molecules, have been studied. (i) It has been found that strong coupling of the cavity with one molecular eigenstate (S0→S1 transition) does not perturb the energies of the other molecular states. (ii) The S0→S2 absorption transition is too weak to strongly couple to the resonant cavity (“λ” standing wave mode). However, the resonant cavity causes a blue shift of the S0→S2 excitation band. (iii) The splitting of the dispersion curve is theoretically predicted and experimentally observed at strong coupling of the cavity resonance (“λ” standing wave mode) with the material resonances of Ag, including bound electron and “epsilon equal zero” transitions.

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“…Rhodamine 6G (R6G) is a fluorophore with well-known optical properties, such as radiative and non-radiative decay rates, and absorption and SE cross sections (Fig. 1(b)) [35][36][37][38]. Its quantum yield is 0.9 and the fluorescence lifetime is 3.9 ns.…”

Section: Cuvette Measurementsmentioning

confidence: 99%

“…The model input parameters were the known concentration, the measured pump and probe fluences, and the optical properties of R6G, such as σ a (λ), σ se (λ), k vib , and k f [35][36][37][38]. Fig.…”

Section: Cuvette Measurements In R6g Solutionsmentioning

confidence: 99%

Photoacoustic imaging of fluorophores using pump-probe excitation

Märk

Schmitt

Theiss

et al. 2015

Biomed. Opt. Express

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A pump-probe technique for the detection of fluorophores in tomographic PA images is introduced. It is based on inducing stimulated emission in fluorescent molecules, which in turn modulates the amount of thermalized energy, and hence the PA signal amplitude. A theoretical model of the PA signal generation in fluorophores is presented and experimentally validated on cuvette measurements made in solutions of Rhodamine 6G, a fluorophore of known optical and molecular properties. The application of this technique to deep tissue tomographic PA imaging is demonstrated by determining the spatial distribution of a near-infrared fluorophore in a tissue phantom. 1983). 32. E. Zhang, J. Laufer, and P. Beard, "Backward-mode multiwavelength photoacoustic scanner using a planar Fabry-Perot polymer film ultrasound sensor for high-resolution three-dimensional imaging of biological tissues," Appl.

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Transient excited singlet state absorption in Rhodamine 6G

Cited by 25 publications

References 12 publications

Control of the Stokes Shift with Strong Coupling

Control of the Stokes Shift with Strong Coupling

Coupling of the First and Second Excited States of R6G Dye with the Fabry–Perot Cavity

Photoacoustic imaging of fluorophores using pump-probe excitation

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