Two-photon spectroscopy of the Schiff base of all-trans-retinal. Nature of the low-lying π π* singlet states

1985 ◽  
Vol 63 (7) ◽  
pp. 1967-1971 ◽  
Author(s):  
Lionel P. Murray ◽  
Robert R. Birge
Keyword(s):  
Excitation Spectrum ◽  
Polarized Light ◽  
Wavelength Region ◽  
Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
The One ◽  
Photon Spectra ◽  
Π State ◽  
Two Photon Excitation

The two-photon excitation spectrum of all-trans-N-retinylidene-n-butylamine (ATRSB) in EPA at 77 K is obtained over the wavelength region from 370 to 455 nm (λex/2) using linearly polarized light. The two-photon excitation maximum is observed at ~422 nm (λex/2) and is red shifted ~2800 cm−1 from the one-photon absorption maximum at ~377 nm. We assign the two-photon excitation spectrum to the "1Ag*−" ← S0 transition which indicates that the "1Ag*−" π π* state lies below the "1Bu*+" π π* state in ATRSB. Comparisons of the one-photon absorption, two-photon excitation, and fluorescence spectra of ATRSB with the corresponding spectra of all-trans-retinal are presented. PPP-CISD calculations correctly predict the directions but not the magnitudes of the blue shifts of the π π* excited state transition energies in going from all-trans-retinal to ATRSB. We postulate that the "1Ag*−" π π* state is preferentially stabilized relative to both the ground state and the nearby "1Bu*+" state by hydrogen bonding to solvent molecules. Comparison of the spectra reported here with the two-photon spectra of rhodopsin provides further evidence that the chromophore in rhodopsin is protonated.

Two-Photon Excitation Imaging of Glucose Metabolism in Living Tissue

1997 ◽  
Vol 3 (S2) ◽  
pp. 305-306
Author(s):  
David W. Piston
Keyword(s):  
Confocal Microscopy ◽  
Collection Efficiency ◽  
Three Dimensional ◽  
Spatial Filter ◽  
Input Power ◽  
Photon Absorption ◽  
Focal Volume ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. It provides three-dimensional resolution and eliminates background equivalent to an ideal confocal microscope without requiring a confocal spatial filter, whose absence enhances fluorescence collection efficiency. This results in inherent submicron optical sectioning by excitation alone. In practice, TPEM is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 limits the average input power to less than 10 mW, only slightly greater than the power normally used in confocal microscopy. Because of the intensity-squared dependence of the two-photon absorption, the excitation is limited to the focal volume.

scholarly journals Two-Photon–NIR-II Antimicrobial Graphene-Nanoagent for Ultraviolet–NIR Imaging and Photoinactivation

2021 ◽  
Author(s):  
WEN-SHUO KUO ◽  
Chia-Yuan Chang ◽  
Ping-Ching Wu ◽  
Jiu-Yao Wang
Keyword(s):  
Photodynamic Therapy ◽  
Quantum Yield ◽  
Chemical Modification ◽  
Near Infrared ◽  
Photon Absorption ◽  
Excitation Wavelength ◽  
Strong Electron ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Abstract BackgroundNitrogen doping and amino-group functionalization, which result in strong electron donation, can be achieved through chemical modification. Large π-conjugated systems of graphene quantum dot (GQD)-based materials acting as electron donors can be chemically manipulated with low two-photon excitation energy in a short photoexcitation time for improving the charge transfer efficiency of sorted nitrogen-doped amino acid–functionalized GQDs (sorted amino-N-GQDs). ResultsIn this study, a self-developed femtosecond Ti-sapphire laser optical system (222.7 nJ pixel−1 with 100-170 scans, approximately 0.65-1.11 s of total effective exposure times; excitation wavelength: 960 nm in the near-infrared II region) was used for chemical modification. The sorted amino-N-GQDs exhibited enhanced two-photon absorption, post-two-photon excitation stability, two-photon excitation cross-section, and two-photon luminescence through the radiative pathway. The lifetime and quantum yield of the sorted amino-N-GQDs decreased and increased, respectively. Furthermore, the sorted amino-N-GQDs exhibited excitation-wavelength-independent photoluminescence in the near-infrared region and generated reactive oxygen species after two-photon excitation. An increase in the size of the sorted amino-N-GQDs boosted photochemical and electrochemical efficacy and resulted in high photoluminescence quantum yield and highly efficient two-photon photodynamic therapy. ConclusionThe sorted dots can be used in two-photon contrast probes for tracking and localizing analytes during two-photon imaging in a biological environment and for conducting two-photon photodynamic therapy for eliminating infectious microbes.

Two-photon excitation spectroscopy of photosynthetic light-harvesting complexes and pigments

2019 ◽  
Vol 216 ◽  
pp. 494-506 ◽  
Author(s):  
Alexander Betke ◽  
Heiko Lokstein
Keyword(s):  
Spectral Region ◽  
Protein Complexes ◽  
Photosynthetic Pigment ◽  
Photon Absorption ◽  
Light Harvesting Complexes ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Pigment Protein Complexes ◽  
Two Photon Excitation

Two-photon excitation (TPE) profiles of LHCII samples containing different xanthophyll complements were measured in the presumed 11Ag− → 21Ag− (S0 → S1) transition region of xanthophylls. Additionally, TPE profiles of Chls a and b in solution and of WSCP, which does not contain carotenoids, were measured. The results indicate that direct two-photon absorption by Chls in the presumed S0 → S1 transition spectral region of carotenoids is dominant over that of carotenoids, with negligible contributions of the latter. These results suggest the re-evaluation of previously published TPE data obtained with photosynthetic pigment–protein complexes containing (B)Chls and carotenoids.

scholarly journals Ligand shell size effects on one- and two-photon excitation fluorescence of zwitterion functionalized gold nanoclusters

2019 ◽  
Vol 21 (43) ◽  
pp. 23916-23921 ◽  
Author(s):  
Martina Perić ◽  
Željka Sanader Maršić ◽  
Isabelle Russier-Antoine ◽  
Hussein Fakhouri ◽  
Franck Bertorelle ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Effects ◽  
Gold Nanoclusters ◽  
Shell Size ◽  
Two Photon ◽  
Photon Excitation ◽  
Ligand Shell ◽  
Aqueous Solvent ◽  
The One ◽  
Two Photon Excitation

The effects of explicit ligands and of aqueous solvent on optical properties and in particular on the one- and two-photon excitation fluorescence of zwitterion functionalized gold nanoclusters have been studied.

Two-photon excitation spectrum of perylene in solution

1990 ◽  
Vol 167 (1-2) ◽  
pp. 85-89 ◽  
Author(s):  
Jeong-A Yu ◽  
Daniel G. Nocera ◽  
George E. Leroi
Keyword(s):  
Excitation Spectrum ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Two-Photon Excitation of Potentiometric Probes Enables Optical Recording of Action Potentials From Mammalian Nerve Terminals In Situ

2008 ◽  
Vol 99 (3) ◽  
pp. 1545-1553 ◽  
Author(s):  
Jonathan A. N. Fisher ◽  
Jonathan R. Barchi ◽  
Cristin G. Welle ◽  
Gi-Ho Kim ◽  
Paul Kosterin ◽  
...  
Keyword(s):  
Action Potentials ◽  
Optical Recording ◽  
Photon Absorption ◽  
Nerve Terminals ◽  
Electrode Arrays ◽  
Two Photon ◽  
Photon Excitation ◽  
Mammalian Nerve ◽  
Two Photon Excitation

We report the first optical recordings of action potentials, in single trials, from one or a few (∼1–2 μm) mammalian nerve terminals in an intact in vitro preparation, the mouse neurohypophysis. The measurements used two-photon excitation along the “blue” edge of the two-photon absorption spectrum of di-3-ANEPPDHQ (a fluorescent voltage-sensitive naphthyl styryl-pyridinium dye), and epifluorescence detection, a configuration that is critical for noninvasive recording of electrical activity from intact brains. Single-trial recordings of action potentials exhibited signal-to-noise ratios of ∼5:1 and fractional fluorescence changes of up to ∼10%. This method, by virtue of its optical sectioning capability, deep tissue penetration, and efficient epifluorescence detection, offers clear advantages over linear, as well as other nonlinear optical techniques used to monitor voltage changes in localized neuronal regions, and provides an alternative to invasive electrode arrays for studying neuronal systems in vivo.

Zeeman effect in the two-photon excitation spectrum of the C 2Π state of NO

1991 ◽  
Vol 156 (3) ◽  
pp. 509-522 ◽  
Author(s):  
S. Guizard ◽  
N. Shafizadeh ◽  
D. Chapoulard ◽  
M. Horani ◽  
D. Gauyacq
Keyword(s):  
Excitation Spectrum ◽  
Zeeman Effect ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

The two-photon excitation spectrum of fluorene near 6 K

1978 ◽  
Vol 30 (3) ◽  
pp. 343-351 ◽  
Author(s):  
A. Bree ◽  
M. Edelson ◽  
C. Taliani
Keyword(s):  
Excitation Spectrum ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Two Photon Excitation Spectrum of a Twisted Quadruple Bond Metal−Metal Complex

1999 ◽  
Vol 121 (4) ◽  
pp. 868-869 ◽  
Author(s):  
Daniel S. Engebretson ◽  
Evan M. Graj ◽  
George E. Leroi ◽  
Daniel G. Nocera
Keyword(s):  
Metal Complex ◽  
Excitation Spectrum ◽  
Two Photon ◽  
Quadruple Bond ◽  
Photon Excitation ◽  
Metal Metal ◽  
Two Photon Excitation

Two‐photon excitation spectrum of benzene in the gas phase and the crystal

1974 ◽  
Vol 60 (1) ◽  
pp. 317-318 ◽  
Author(s):  
Robin M. Hochstrasser ◽  
J. E. Wessel ◽  
H. N. Sung
Keyword(s):  
Gas Phase ◽  
Excitation Spectrum ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation
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