Jablonski diagrams fluorescence

JABLONSKI DIAGRAM FLUORESCENCE ABSORPTION SPECTROSCOPY n TT TRANSITION a TRANSITION 7T 7T TRANSITION Electron microscopy,... 

FIGURE 7.4 Modified Jablonski diagram showing transitions between excited states and the ground state. Radiative processes are shown by straight lines, radiationless processes by wavy lines. IC = internal conversion ISC = intersystem crossing, vc = vibrational cascade hvf = fluorescence hVp = phosphorescence. 

Jablonski (48-49) developed a theory in 1935 in which he presented the now standard Jablonski diagram" of singlet and triplet state energy levels that is used to explain excitation and emission processes in luminescence. He also related the fluorescence lifetimes of the perpendicular and parallel polarization components of emission to the fluorophore emission lifetime and rate of rotation. In the same year, Szymanowski (50) measured apparent lifetimes for the perpendicular and parallel polarization components of fluorescein in viscous solutions with a phase fluorometer. It was shown later by Spencer and Weber (51) that phase shift methods do not give correct values for polarized lifetimes because the theory does not include the dependence on modulation frequency. 

Figure 10. Electron excitations in radicals (a) Collective representation of one-electron transitions of the A, B, and C types if denotes MO (b) LCI energy-level scheme (Jablonski diagram) for doublet and quartet states indicating why with radicals fluorescence (- - -) but not phosphorescence is observed. Spin-forbidden transitions are represented by dashed lines.

Figure 9.1. A Jablonski diagram. So and Si are singlet states, Ti is atriplet state. Abs, absorption F, fluorescence P, phosphorescence IC, internal conversion and ISC, intersystem crossing. Radiative transitions are represented by full lines and nonradiative transitions by dashed lines...

Fig. 1 Jablonski diagram of energy level for describing processes absorption, fluorescence and phosphorescence in complex molecules where kf and /c arc the radiative and nonradiative rates of fluorescence, respectively, kj and kTnr are the radiative and nonradiative rates of phosphorescence, respectively, k-lsc is the interconversion rate, and kmt is the rate of intermolecular processes Av denotes the Stokes shift of fluorescence...

Fluorescent molecules can participate in different intermolecular reactions starting from Si state with rate klnl as a result, their properties, such as the quantum yield, , and the fluorescence lifetime, x, can change. The proper equations for x and , as illustrated in Jablonski diagram (Fig. 1), may be written as [1, 2] ... 

Just as above, we can derive expressions for any fluorescence lifetime for any number of pathways. In this chapter we limit our discussion to cases where the excited molecules have relaxed to their lowest excited-state vibrational level by internal conversion (ic) before pursuing any other de-excitation pathway (see the Perrin-Jablonski diagram in Fig. 1.4). This means we do not consider coherent effects whereby the molecule decays, or transfers energy, from a higher excited state, or from a non-Boltzmann distribution of vibrational levels, before coming to steady-state equilibrium in its ground electronic state (see Section 1.2.2). Internal conversion only takes a few picoseconds, or less [82-84, 106]. In the case of incoherent decay, the method of excitation does not play a role in the decay by any of the pathways from the excited state the excitation scheme is only peculiar to the method we choose to measure the fluorescence (Sections 1.7-1.11). 

Fluorescence is a process that occurs after excitation of a molecule with light. It involves transitions of the outermost electrons between different electronic states of the molecule, resulting in emission of a photon of lower energy than the previously absorbed photon. This is represented in the Jablonski diagram (see Fig. 6.1). As every molecule has different energy levels, the fluorescent properties vary from one fluorophore to the other. The main characteristics of a fluorescent dye are absorption and emission wavelengths, extinction... 

Fig. 6.1. Jablonski diagram, representing electron energy levels of fluorophores and transitions after photon excitation. S = electronic state, different lines within each state represent different vibrational levels. Blue arrows represent absorption events, green arrows depict internal conversion or heat dissipation, and orange arrows indicate fluorescence emission. Intersystem crossing into triplet states has been omitted for simplicity (see also Chaps. 1 and 12).

Fig. 21. Top The general Jablonski diagram for the flavin chromophore. The given wavelengths for absorption and luminescence represent crude average values derived from the actual spectra shown below. Due to the Franck-Condon principle the maxima of the peak positions generally do not represent so-called 0 — 0 transitions, but transitions between vibrational sublevels of the different electronically excited states (drawn schematically). Bottom Synopsis of spectra representing the different electronic transitions of the flavin nucleus. Differently substituted flavins show slightly modified spectra. Absorption (So- - S2, 345 nm S0 -> Si,450nm 1561) fluorescence (Sj — S0) 530 nm 156)) phosphorescence (Ty Sq, 605 nm 1051) triplet absorption (Tj ->Tn,...

Figure 1 Jablonski diagram showing energy levels and transitions F, fluorescence C, chemiluminescence P, phosphorescence CD, collisional deactivation IC, internal conversion ISC, intersystem crossing S0, ground singlet state S1( S2, excited singlet states Tl5 excited triplet state.

Fig. 9. Jablonsky Diagram for energy conversion pathways of an excited molecule. While fluorescence occurs between states of the same spin, an ISC (inter system crossing) leads to spin inversion and a delay in emission (phosphorescence halftimes from 1CT4 s to minutes or even hours)...

Figure 4.12 Jablonski diagram for the deactivation of a molecule by emission of E-type delayed fluorescence...

The Jablonski diagram for thermally-activated delayed fluorescence is shown in Figure 4.12. 

Fig. 6 Modified Jablonski diagram for illustrating metal-fluorophore interactions, (a) the transition of dye excited by the incident light, (b) the enhanced excitation according to enlarged electromagnetic field, (c) the fluorescent emission of dye molecule, (d) the nonradiative relaxation, (e) the enhanced emission of the fluorophores and metal coupling in far field. Reproduced with permission from Ref. [77]...

The Perrin-Jablonski diagram (Figure 3.1) is convenient for visualizing in a simple way the possible processes photon absorption, internal conversion, fluorescence, intersystem crossing, phosphorescence, delayed fluorescence and triplet-triplet transitions. The singlet electronic states are denoted S0 (fundamental electronic state), Si, S2,... and the triplet states, Ti,T2,. Vibrational levels are associated with each electronic state. It is important to note that absorption is very fast ( 10 15 s) with respect to all other processes (so that there is no concomitant... 

Fig. 3.1. Perrin-Jablonski diagram and illustration of the relative positions of absorption, fluorescence and phosphorescence spectra.

Figure 10.3. Modified Jablonski diagram for the processes of absorption and fluorescence emission (left), dynamic quenching (middle), and fluorescence resonance energy transfer (FRET) (right).

The most likely electronic transition will occur without changes in the positions of the nuclei (e.g., little change in the distance between atoms) in the molecular entity and its environment. Such a state is known as a Franck-Condon state, and the transition is referred to as a vertical transition. In such transitions, the intensity of the vibronic transition is proportional to the square of the overlap interval between the vibrational wavefunctions of the two states. See Fluorescence Jablonski Diagram Comm, on Photochem. (1988) Pure and Appl. Chem. 60, 1055. 

Long-lived luminescence. 2. Luminescence involving a change in spin multiplicity (e.g., triplet-to-singlet, singlet-to-triplet, quartet state-to-doublet state, etc.). See Fluorescence Jablonski Diagram... 

BURST KINETICS FRAGMENTATION FRANCK-CONDON PRINCIPLE FLUORESCENCE JABLONSKI DIAGRAM FRAP,... 

JABLONSKI DIAGRAM RADIATIONLESS TRANSITION FLUORESCENCE RADIATIVE LIFETIME RADICAL (or, FREE RADICAL)... 

FIGURE 7.5 A Jablonski diagram. The solid horizontal lines represent molecular orbitals, with singlet states on the left and triplet states on the right. The arrows represent transitions between these levels, with straight lines for radiative transitions and wavy lines for non-radiative transitions. For the radiative transitions, absorption corresponds to the upward arrows at left, fluorescence corresponds to the downward arrows, and phosphorescence is represented by the diagonal arrow from Tj to Sq. 

Figure 5.10 Jablonski diagram for E-type delayed fluorescence.

Figure 12.1—Energy diagram comparing fluorescence and phosphorescence. Short arrows correspond to internal conversion without the emission of photons. Fluorescence is an energy transfer between states of the same multiplicity (spin state) while phosphorescence is between states of diiferent multiplicity. The situation is more complex than that shown by this Jablonski diagram.

Fig. 10. Jablonski diagram showing the near-degenerate A[S]A [T] X and )K[S]K IT] K states at Q % Q0. Some primary photochemical processes are (/) absorption, (/ ) fluorescence, (//) and (ii") intersystem crossing, (ii7) and (iii ) vibrational relaxation and excitation, and (iv) phosphorescence.

Figure 3.23 Jablonski diagram of the transitions between electronic states of a polyatomic molecule. Hc> stands for internal conversion, isci for intersystem crossing, V and (a for absorption of light, f for fluorescence and (p> for phosphorescence...

Figure 3.29 (a) Outline of the absorption, A fluorescence, F and phosphorescence, P spectra of a rigid polyatomic molecule. X = wavelength, vertical axis = absorbance (A) or emission intensity (F, P). (b) The Stokes shift of the absorption and fluorescence spectra is defined as the difference between their maxima. When this shift is small, there is a substantial spectral overlap between absorption and emission, (c) Jablonski diagram and outline of the absorption and fluorescence spectra of azulene, an exception to Kasha s rule. The energy gap between S0 and Sj is very small, that between Sj and S2 is very large... 

Figure 4.25 Jablonski diagram of the heavy atom effect on photochemical reactivity. If excitation to S2 (hv2) is followed by intersystem crossing (isc) to T2, the quantum yield of reaction R decreases at higher excitation energies, ic = internal conversion, a = absorption, f = fluorescence, p = phosphorescence...

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