Two-Photon Absorption and Fluorescence

Nonlinear optics (NLO) is the branch of optics that describes the behavior of light in nonlinear media, in which the dielectric polarization P responds nonlinearly to the electric field E of the light. This nonlinearity is typically observed only at very high light intensities such as those provided by pulsed lasers. 

Time-dependent density functional theory studies of the photoswitching of the two-photon absorption spectra in stilbenes were reported [15]. The one- and two-photon absorption characteristics of the open- and closed-ring isomers of 1-3 have been 

Jt-electron system, a large change in dipole moment upon transition to the excited state, and a large transition moment The two-photon absorption cross section was calculated as high as 881.34 x 10 ° cm s/photort 

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The one- and two-photon excited fluorescence property and crystal structure of a substituted stilbene-type compound frans-4-diethylamino-4 -bromostilbene (DEARS) has been reported [17]. Results indicate that this compound has a strong two-photon-exdted blue fluorescence at 440 nm when the 700 nm laser is used as the pump source. The one- and two-photon absorption and fluorescence properties of a free radical photopolymerization initiator, ( , )-4- 2-[p -(]yf,N-di-w-butylamino)stil-ben-p-yl]vinyl pyridine (Figure 3.8), in various solvents have been investigated [18]. The dye has a moderate two-photon absorption cross section of = 0.91 x 10 cm s/photon at 532 nm. This compound showed a strong two-photon-induced blue fluorescence of432 nm when pumped with 800 nm laser irradiation. Quantum chemical calculation indicated that the new initiator possesses a large delocalized... 

Lindek St, Cremer Chr and Stelzer E H K 1996 Confocal theta fluorescence microscopy using two-photon absorption and annular apertures Optik 02 131-4... 

S2 - Sq fluorescence and radiationless transitions from the state of porphyrins have been studied in order to reveal photodynaunics of porphyrins. The S2 state fluorescence of zinc(II)-tetraphenylporphin is caused even by the excitation to the state. Two-photon absorption and optical-optical double resonance studies show that a stepwise two-photon absorption through the state is a main process populating the S2 state. 

Sun Y-F, Huang W, Lu C-G et al (2009) The synthesis, two-photon absorption and blue upconversion fluorescence of novel, nitrogen-containing heterocyclic chromophores. Dye Pigment 81 10-17... 

FITC+FAM (fluorescein derivatives). ECFP, EGFP, EYFP (enhanced—cyan, green and yellow fluorescent protein, respectively, Clontech Laboratories, Inc., USA). Bodipy is a trademark of Invitrogen Ltd., UK. Attoxxxis a trademark of ATID-TEC GmbH, Gennany. A A S, and A J), A are the one- and two-photon absorption and emission maximum, respectively. QY is the fluorescence quantum yield, SS the Stokes shift, e the molar extinction coefficient and Tf the fluorescence lifetime. Further information regarding two-photon measurements can be found In Chapter 3. 

Canva M., Geordes P., Perelgritz J.F., Brum A., Chaput F., Boilot J.P. Perelene and pyrromethen doped xerogel for a pulsed laser. Appl. Opt. 1995 34(3) 428-431 Canva M., Roger G., Cassagne F., Levey Y., Brun A., Chaput F., Boilot J.P., Rapaport A., Heerdt C., Bass M. Dye-doped sol-gel materials for two-photon absorption induced fluorescence. Opt. 

Lee D and Albrecht A C 1985 A unified view of Raman, resonance Raman, and fluorescence spectroscopy (and their analogues in two-photon absorption) Advances in Infrared and Raman Spectroscopy vo 12, ed R J H Clark and R E Hester (New York Wiley) pp 179-213... 

Fischer A, Cremer C, StelzerEHK (1995) Fluorescence of coumarins and xanthenes after two-photon absorption with a pulsed titanium-sapphire laser. Appl Opt 34 1989-2003... 

Octatetraene is the shortest unsubstituted polyene that exhibits fluorescence. The X kg —> 2 kg transition is clearly seen in one- and two-photon absorption spectra and the 2 kg is unambiguously identified to be the lowest singlet state1. 

At a fundamental wavelength of 1064 nm, large and anisotropic optical nonlinearity was also observed. The values of X (3) and are 4.5 x 1010 esu and 1.0 x 10 10 esu, respectively. The large values are due to the two photon resonance, because the harmonic wavelength of 355 nm is near off-resonance region. From the two-photon fluorescence measurement, we confirmed that a two-photon absorption band, which is origin of the enhancement effect, exist around 532 nm, half of the fundamental wavelength. 

Przhonska OV, Webster S, Padilha LA et al (2010) Two-photon absorption in near-IR conjugated molecules design strategy and structure-property relations. In Demchenko AP (ed) Advanced fluorescence reporters in chemistry and biology. I. Springer Ser Fluoresc 8 105-147... 

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