Importance of initial and final states as intermediate states in two-photon spectroscopy of polar molecules

Dick, Bernhard; Hohlneicher, Georg

doi:10.1063/1.442971

Cited by 127 publications

(89 citation statements)

References 16 publications

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“…This is motivated by static dipole moments observed to differ from zero for the S 0 and the S 2 states of lattice distorted DPOT. 35,36 We take these transition probabilities as ''intrinsic,'' though dependent on the lattice environment. A complicated intensity pattern is expected from the linear combination of the moments through the S 1 -S 2 state mixing.…”

Section: Two-photon Excitation "Tpe…mentioning

confidence: 99%

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Symmetry breaking and spectra of diphenyloctatetraene in n-alkanes

Walser

Zumofen

Plakhotnik

2000

The Journal of Chemical Physics

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Articles you may be interested inElectronic spectra of azaindole and its excited state mixing: A symmetry-adapted cluster configuration interaction study J. Chem. Phys. 143, 204304 (2015); 10.1063/1.4935578The elusive S 2 state, the S 1/S 2 splitting, and the excimer states of the benzene dimer J. Chem. Phys. 142, 234306 (2015) One-and two-photon excitation spectra, as well as absorption and emission spectra of diphenyloctatetraene ͑DPOT͒ in n-alkanes are investigated at low temperatures. For DPOT in n-octane we report on the measurements of one-photon excitation and emission spectra and for DPOT in n-tetradecane ͑TD͒ on the measurements of one-and two-photon excitation spectra and emission spectra. The spectra are governed by the transitions between the electronic ground (S 0 ) and the two lowest electronic excited singlet states (S 1 ,S 2 ). The interpretation is based on allowed transitions and transitions induced by the S 1 -S 2 coupling due to Herzberg-Teller promoting modes or due to static lattice-induced distortions of DPOT. A single noncentrosymmetric site is observed for DPOT in n-octane. For DPOT in TD a centrosymmetric and a noncentrosymmetric site are reported. The analysis indicates that there is a dynamical equilibrium in the population of these two sites. The experimental data are quantitatively studied by comparison with simulated spectra. The simulation calculations are based on the coupling between nonadiabatic S 1 and S 2 states, harmonic modes, and suitable transition moments and line-shape functions. For DPOT in TD the calculations reveal an interesting interference pattern in the vibronic progressions observed in two-photon excitation spectra.

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Section: Two-photon Excitation "Tpe…mentioning

confidence: 99%

“…Following the discussion in Ref. 36, we separate the contributions of the ͉i͘ϭ͉g͘ and ͉i͘ϭ͉e͘ states in the sum of Eq. ͑15͒ leading to…”

Section: Two-photon Excitation "Tpe…mentioning

confidence: 99%

Symmetry breaking and spectra of diphenyloctatetraene in n-alkanes

Walser

Zumofen

Plakhotnik

2000

The Journal of Chemical Physics

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“…In the context of multiphoton absorption, Meath and Power demonstrated that the twolevel approximation is indeed never valid when deployed with a minimal-coupling Hamiltonian, since this kind of formulation requires sum rules to be applied over all levels in order to secure a usable result for the quantum amplitude [12]. It is interesting to reflect that the results of the theorem delivered in the present paper apply to both forms of coupling, addressing the matrix elements of both momentum and electric dipole operators.…”

Section: Discussionmentioning

confidence: 99%

“…With the typical intensity levels of pulsed laser light, there arises a significant probability for two or more photons to interact simultaneously (within the limits of quantum uncertainty) with each optically distinct center. Although the materials that are most effective for the utilization of optical nonlinearity in frequency conversion (especially second harmonic generation, SHG) are those whose energy level structures are significantly more complex than atoms, the two-level approximation has received wide application in such a context [5,[11][12][13][14][15][16][17][18]; it not only delivers results of a relatively simple form, it also relates well to long-established concepts of chemical structure. A wealth of synthetic studies have built on the anticipated and oft-proven connection between 'push-pull' chromophore structures [19][20][21][22] (facilitating intramolecular electron transfer) and an enhanced second harmonic response.…”

Section: Introductionmentioning

confidence: 99%

Perturbation theory and the two-level approximation: A corollary and critique

Andrews

Coles

2011

Chemical Physics Letters

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a b s t r a c tThis analysis addresses the use of a two-level approximation to simplify expressions derived from perturbation theory. It is shown that the limitations of validity for the emergent results are more stringent than is commonly understood, being equivalent in effect to the adoption of a more extensive approximationone that significantly undermines the perturbative origin of those expressions. Effectively truncating the completeness relation, a series of interconnected operator relations comes into play, some with physically untenable consequences. A new theorem on the expectation values of operator functions highlights additional constraints upon any molecule modelled as a two-level system.

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“…a two-state model may be applied. 15,16,18,20,[22][23][24][25][26][27][28][43][44][45][46][47][48][49][50][51][52] To be clear, the assumption is that the character of the fluorescence emission process, including the effect of the probe radiation, is dominated by two electronic levels; it is not to be presumed that the state from which the fluorescence decay occurs is necessarily the same as the state initially populated by photoexcitation. …”

Section: Two-level Systemsmentioning

confidence: 99%

Laser-Controlled Fluorescence in Two-Level Systems

Leeder

Andrews

2010

J. Phys. Chem. B

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The ability to modify the character of fluorescent emission by a laser-controlled, optically nonlinear process has recently been shown theoretically feasible, and several possible applications have already been identified. In operation, a pulse of off-resonant probe laser beam, of sufficient intensity, is applied to a system exhibiting fluorescence, during the interval of excited state decay following the initial excitation. The result is a rate of decay that can be controllably modified, the associated changes in fluorescence behavior affording new, chemically-specific information. In this paper, a two-level emission model is employed in the further analysis of this all-optical process; the results should prove especially relevant to the analysis and imaging of physical systems employing fluorescent markersthese ranging from quantum dots to green fluorescence protein. Expressions are presented for the lasercontrolled fluorescence anisotropy exhibited by samples in which the fluorophores are randomly oriented. It is also shown that, in systems with suitably configured electronic levels and symmetry properties, fluorescence emission can be produced from energy levels that would normally decay nonradiatively.2

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Importance of initial and final states as intermediate states in two-photon spectroscopy of polar molecules

Cited by 127 publications

References 16 publications

Symmetry breaking and spectra of diphenyloctatetraene in n-alkanes

Symmetry breaking and spectra of diphenyloctatetraene in n-alkanes

Perturbation theory and the two-level approximation: A corollary and critique

Laser-Controlled Fluorescence in Two-Level Systems

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