Two-photon electric-dipole selection rules

Bonin, Keith; McIlrath, T. J.

doi:10.1364/josab.1.000052

Cited by 159 publications

(128 citation statements)

References 3 publications

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“…The states accessed via two-photon transitions are dark states for the 1PA process (see Table I), what is due to its molecular symmetry (centrosymmetry) and the distinct selection rules of the one-and two-photon absorption processes. 54 The theoretical results indicate four 2PA allowed states for b-apo-8 0 -carotenal, located at 472, 329, 317, and 273 nm. In this case, the 2PA allowed states are slightly allowed via 1PA, while the strongly 1PA allowed state S 1 is only slightly allowed via 2PA, as expected due to the relaxation of the electric-dipole selection rules for noncentrosymmetric molecules, 54 such as b-apo-8 0 -carotenal.…”

Section: -mentioning

confidence: 92%

Two-photon absorption spectra of carotenoids compounds

Vivas

Silva

Boni

et al. 2011

Journal of Applied Physics

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Carotenoids are biosynthetic organic pigments that constitute an important class of one-dimensional p-conjugated organic molecules with enormous potential for application in biophotonic devices. In this context, we studied the degenerate two-photon absorption (2PA) cross-section spectra of two carotenoid compounds (b-carotene and b-apo-8 0 -carotenal) employing the conventional and whitelight-continuum Z-scan techniques and quantum chemistry calculations. Because carotenoids coexist at room temperature as a mixture of isomers, the 2PA spectra reported here are due to samples containing a distribution of isomers, presenting distinct conjugation length and conformation. We show that these compounds present a defined structure on the 2PA spectra, that peaks at 650 nm with an absorption cross-section of approximately 5000 GM, for both compounds. In addition, we observed a 2PA band at 990 nm for b-apo-8 0 -carotenal, which was attributed to a overlapping of 1 1 B u þ -like and 21 Ag --like states, which are strongly one-and two-photon allowed, respectively. Spectroscopic parameters of the electronic transitions to singlet-excited states, which are directly related to photophysical properties of these compounds, were obtained by fitting the 2PA spectra using the sum-over-states approach. The analysis and interpretations of the 2PA spectra of the investigated carotenoids were supported by theoretical predictions of one-and two-photon transitions carried out using the response functions formalism within the density functional theory framework, using the long-range corrected CAM-B3LYP functional.

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Section: -mentioning

confidence: 92%

Two-photon absorption spectra of carotenoids compounds

Vivas

Silva

Boni

et al. 2011

Journal of Applied Physics

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“…Additionally, the 3PA spectra for compounds II, III and IV present a band around 1180 nm that correspond to an one-photon allowed state located between 380 -400 nm. Such transitions are allowed because the electric-dipole selection rules [18] are the same to both types of process (1PA and 3PA). To confirm the actual three-photon absorption nature of the observed results (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, we observed the presence of a 3PA band around 1180 nm for the compounds II, III and IV, which correspond to one-photon allowed state located in the UV-blue region. These transitions are 3PA allowed since the electric-dipole selection rules [18] are the same for both types of process (1PA and 3PA). Employing the sum-overessential-states approach, we were able to associate the 3PA cross-section exhibited by the platinum acetylide complexes to basically two dominant contributions: one relate to a change in the permanent dipole moment and other one corresponding to a three-photon transition intermediate by a two-photon allowed state.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, it is necessary to take into account the intermediate energy levels. In addition, non-centrosymmetric molecules do not follow the dipole-electric selection rule [18] and, therefore, one-(or three-) and two-photon transitions are allowed between any levels. In this case, taking into account the average over all possible molecular orientations in an isotropic medium and considering that only one intermediate state, e (one and two-photon allowed), contributes significantly to the transition matrix elements, the 3PA cross-section can be written as (assuming linearly polarized light): never in close resonance with excitation photons in a degenerate 3PA process [19].…”

Section: Interpretation Of the 3pa Cross-sectionmentioning

confidence: 99%

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Broadband three-photon absorption spectra of platinum acetylide complexes

Vivas

Piovesan

Silva

et al. 2011

Opt. Mater. Express

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Abstract:We investigate the three-photon absorption spectra of four platinum acetylides complexes employing femtosecond pulses. We observed strong three-photon absorption cross-section in the near-infrared region (from 850 nm to 1200 nm). The three-photon absorption (3PA) spectra present resonance enhancement effect as two photons of the excitation wavelength approach the lower two-photon allowed states of the molecules as well as a 3PA allowed band around 1180 nm. The 3PA crosssection spectra were interpreted using the sum-over-essential-states approach, considering a three-energy-level diagram.

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“…As a consequence of the fact that photons obey Bose-Einstein statistics, atomic 2E1, J ¼ 1 ! J 0 ¼ 0 amplitudes are forbidden for photons of the same energy [17,27]. As a result, the continuum distribution of the twophoton decay of the 3 S 1 level is suppressed at the midpoint where the two photons would share the transition energy equally.…”

Section: Introductionmentioning

confidence: 99%

Two-Photon Decay in Heavy Atoms and Ions

Mokler¹,

Dunford²

2004

Phys. Scr.

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We review the status of and comment on current developments in the field of two-photon decay in atomic physics research. Recent work has focused on twophoton decays in highly-charged ions and two-photon decay of inner-shell vacancies in heavy neutral atoms. We emphasize the importance of measuring the shape of the continuum emission in two-photon decay as a probe of relativistic effects in the strong central fields found in heavy atomic systems. New experimental approaches and their consequences will be discussed.

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Two-photon electric-dipole selection rules

Cited by 159 publications

References 3 publications

Two-photon absorption spectra of carotenoids compounds

Two-photon absorption spectra of carotenoids compounds

Broadband three-photon absorption spectra of platinum acetylide complexes

Two-Photon Decay in Heavy Atoms and Ions

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