Molecular Symmetry and Two-Photon Spectroscopy

Wirth, Mary J.; Koskelo, Aaron C.; Sanders, M. J.

doi:10.1366/0003702814731888

Cited by 58 publications

(46 citation statements)

References 16 publications

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“…As the energy of either photon approaches onephoton resonance with the lowest excited state ͑7.6 eV for the isolated molecule͒, the 2PA transition strength increases due to preresonant enhancement. Similar to the more familiar case of preresonant enhancement of Raman cross sections, the increase in 2PA strength comes from the resonance term in the denominator of the expression for the two-photon transition dipole tensor elements, 4 …”

Section: A Calculated Two-photon Cross Sectionsmentioning

confidence: 97%

“…The simultaneous absorption of two photons occurs through coupling of two transition dipole moments, thus the variation of the absorption cross section with the relative polarization of the two photons depends on the symmetry of the initial and final states. 1,4 Monson and McClain 1-3 elegantly demonstrated the polarization dependence of the cross section for an orientationally averaged sample and show that the polarization ratio reveals the symmetry of the electronically excited state in favorable cases. The polarization ratio is defined as para / perp , where para and perp are the 2PA cross sections for parallel and perpendicular relative polarization of the pump and probe photons.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] Although there have been numerous applications of two-photon excitation since the invention of the Q-switched laser, including considerable activity to develop two-photon dyes, 5 the continuous two-photon absorption ͑2PA͒ spectrum is rarely available. Recently, two schemes have been developed to record the continuous 2PA spectrum, one based on the Z-scan method using dispersed broadband laser pulses [6][7][8] and the second derived from the broadband femtosecond pump-probe technique.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Elles¹,

Rivera²,

Zhang³

et al. 2009

The Journal of Chemical Physics

106

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Two-photon absorption ͑2PA͒ spectroscopy in the range from 7 to 10 eV provides new insight on the electronic structure of liquid water. Continuous 2PA spectra are obtained via the pump-probe technique, using broadband probe pulses to record the absorption at many wavelengths simultaneously. A preresonance enhancement of the absolute 2PA cross section is observed when the pump-photon energy increases from 4.6 to 6.2 eV. The absorption cross section also depends on the relative polarization of the pump and probe photons. The variation of the polarization ratio across the spectrum reveals a detailed picture of the 2PA and indicates that at least four different transitions play a role below 10 eV. Theoretical polarization ratios for the isolated molecule illustrate the value of the experimental polarization measurement in deciphering the 2PA spectrum and provide the framework for a simple simulation of the liquid spectrum. A more comprehensive model goes beyond the isolated molecule picture and connects the 2PA spectrum with previous one-photon absorption, photoelectron, and x-ray absorption spectroscopy measurements of liquid water. Previously unresolved, overlapping transitions are assigned for the first time. Finally, the electronic character of the vertical excited states is related to the energy-dependent ionization mechanism of liquid water.

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Section: A Calculated Two-photon Cross Sectionsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Elles¹,

Rivera²,

Zhang³

et al. 2009

The Journal of Chemical Physics

106

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“…However, a complete set of molecular parameters for fluorophores in a liquid can only be obtained by exciting with photons of different colours, as shown by McClain and Wirth [5,21], because the experiments have to involve photons of different wavelengths and different polarizations. Wan and Johnson showed that a highly time-resolved analysis is needed as well [22].…”

Section: Introductionmentioning

confidence: 99%

Applications of the time-resolved two-colour two-photon excitation of UV fluorophores using femtosecond laser pulses

et al. 2009

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A short overview of the principles and applications of the two-colour two-photon (2C2P) excitation of fluorescence by using femtosecond pulses is given. Fluorescence is generated by the simultaneous absorption of an 800 nm photon and a 400 nm photon of overlapping laser beams of a titanium:sapphire laser. Two examples of its application are presented: firstly, it is used to monitor the enzymatic cleavage of bovine serum albumin (BSA) by elastase. The fluorescent amino acid tryptophan present in BSA is excited corresponding to an effective one-photon wavelength of 266 nm. Secondly, it is shown how one can utilize the different polarizations of the excited beams for determining the symmetry of the excited states of molecules, exemplarily shown for p-terphenyl in cyclohexane. Further applications and experiments for 2C2P are suggested for using it in UV-fluorescence microscopy and for determining the properties of the electronic states of biomolecules by using differently polarized photons.

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“…The increasing availability of ps and fs lasers has resulted in expanded interest in multi-photon excitation of fluorescence. Since then, two-photon spectroscopy has been used to study the excited state symmetry of organic chromophores [2][3][4]. Two-photon excitation has been applied to study hydrocarbons [5,6], porphyrins [7], polyenes [8,9], protein bound chromophores [10] and indole derivatives [11,12].…”

Section: Multi-photon Excitationmentioning

confidence: 99%

Advances in Fluorescence Spectroscopy: Multi-Photon Excitation, Engineered Proteins, Modulation Sensing and Microsecond Rhenium Metal-Ligand Complexes

et al. 1999

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The technology and applications of fluorescence spectroscopy are rapidly advancing. In this overview presentation we summarize some recent developments from this laboratory. Two and three-photon excitation have been observed for a wide variety of intrinsic and extrinsic fluorophores, including tryptophan, tyrosine, DNA stains, membrane probes, and even alkanes. It has been possible to observe multi-photon excitation of biopolymers without obvious photochemical or photo-thermal effects. Although not described in our lecture, another area of increasing interest is the use of engineered proteins for chemical and clinical sensing. We show results for the glucose-galactose binding protein from E. coli. The labeled protein shows spectral changes in response to micromolar concentrations of glucose. This protein was used with a novel sensing method based on the modulated emission of the labeled proteins and a long lifetime reference fluorophore. And finally, we describe a recently developed rhenium complex which displays a lifetime near 3 µs in oxygenated aqueous solution. Such long lifetime probes allow detection of microsecond dynamic processes, bypassing the usual nanosecond timescale limit of fluorescence. The result of these developments in protein engineering, sensing methods, and metal-ligand probe chemistry will be the increased use of fluorescence in clinical chemistry and point-of-care analyses.

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Molecular Symmetry and Two-Photon Spectroscopy

Cited by 58 publications

References 16 publications

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Applications of the time-resolved two-colour two-photon excitation of UV fluorophores using femtosecond laser pulses

Advances in Fluorescence Spectroscopy: Multi-Photon Excitation, Engineered Proteins, Modulation Sensing and Microsecond Rhenium Metal-Ligand Complexes

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