Excitation Of Two-Photon Intermediate Resonances With The Triplet States At Three-Photon Barium And Strontium Atom Ionization

1986 ◽  
Author(s):  
I I. Bondar ◽  
N B. Delone ◽  
F A. Il'kov ◽  
V V. Suran
Keyword(s):  
Triplet States ◽  
Strontium Atom ◽  
Two Photon ◽  
Atom Ionization

scholarly journals Probing different spin states in xylyl radicals and ions

2018 ◽  
Vol 20 (10) ◽  
pp. 7180-7189 ◽  
Author(s):  
Mathias Steglich ◽  
Andras Bodi ◽  
John P. Maier ◽  
Patrick Hemberger
Keyword(s):  
Photoelectron Spectroscopy ◽  
Triplet States ◽  
Spin States ◽  
Two Photon ◽  
Benzyl Radicals ◽  
Singlet And Triplet States ◽  
Photon Ionization

Resonant one-color two-photon ionization spectroscopy and mass-selected threshold photoelectron spectroscopy were applied to study the electronic doublet states of the three xylyl (methyl-benzyl) radicals above 3.9 eV as well as the singlet and triplet states of the cations up to 10.5 eV.

scholarly journals Dynamic quenching of porphyrin triplet states by two-photon absorbing dyes: Towards two-photon-enhanced oxygen nanosensors

2008 ◽  
Vol 198 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Olga S. Finikova ◽  
Ping Chen ◽  
Zhongping Ou ◽  
Karl M. Kadish ◽  
Sergei A. Vinogradov
Keyword(s):  
Triplet States ◽  
Dynamic Quenching ◽  
Two Photon

scholarly journals Design of metalloporphyrin-based dendritic nanoprobes for two-photon microscopy of oxygen

2008 ◽  
Vol 12 (12) ◽  
pp. 1261-1269 ◽  
Author(s):  
Artem Y. Lebedev ◽  
Thomas Troxler ◽  
Sergei A. Vinogradov
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Dynamic Range ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Triplet States ◽  
Redox Potentials ◽  
Oxygen Quenching ◽  
Two Photon Microscopy ◽  
Two Photon

Metalloporphyrin-based phosphorescent nanoprobes are being developed for two-photon microscopy of oxygen. In these molecular constructs, the generation of porphyrin triplet states following two-photon excitation is induced by the intramolecular Förster-type resonance energy transfer from a covalently attached 2P antenna. In the earlier developed prototypes, electron transfer between the antenna and the metalloporphyrin strongly interferred with the phosphorescence, reducing the sensitivity and the dynamic range of the sensors. By tuning the distances between the antenna and the core, and adjusting their redox potentials, the unwanted electron transfer could be prevented. An array of phosphorescent Pt porphyrins (energy transfer acceptors) and 2P dyes (energy transfer donors) was screened using dynamic quenching of phosphorescence, and the FRET-pair with the minimal ET rate was identified. This pair, consisting of Coumarin-343 and Pt meso-tetra-(4-alkoxyphenyl)porphyrin, was used to construct a probe in which the antenna fragments were linked to the termini of G3 poly(arylglycine) (AG) dendrimer with PtP core. The folded dendrimer formed an insulating layer between the porphyrin and the antenna, simultaneously controlling the rate of oxygen quenching (Stern-Volmer oxygen quenching constant). Modification of the dendrimer periphery with oligoethyleneglycol residues made the probe's signal insensitive to the presence of proteins and other macromolecular solutes.

Two-Photon Chemistry from Upper Triplet States of Thymine

2013 ◽  
Vol 135 (44) ◽  
pp. 16714-16719 ◽  
Author(s):  
Victoria Vendrell-Criado ◽  
Gemma M. Rodríguez-Muñiz ◽  
Minoru Yamaji ◽  
Virginie Lhiaubet-Vallet ◽  
M. Consuelo Cuquerella ◽  
...  
Keyword(s):  
Triplet States ◽  
Two Photon

SPIN CORRELATIONS OF THE FINAL LEPTONS IN THE TWO-PHOTON PROCESSES γγ → e+e-, μ+μ-, τ+τ-

2014 ◽  
Vol 35 ◽  
pp. 1460453
Author(s):  
VALERY V. LYUBOSHITZ ◽  
VLADIMIR L. LYUBOSHITZ
Keyword(s):  
Spin Structure ◽  
Triplet States ◽  
Strongly Correlated ◽  
Correlation Tensor ◽  
Spin Correlations ◽  
Two Photon ◽  
Final Electron ◽  
Singlet And Triplet States ◽  
Explicit Expressions

The spin structure of the process γγ → e+e- is theoretically investigated. It is shown that, if the primary photons are unpolarized, the final electron and positron are unpolarized as well but their spins are strongly correlated. For the final (e+e-) system, explicit expressions for the components of the correlation tensor are derived, and the relative fractions of singlet and triplet states are found. It is demonstrated that in the process γγ → e+e- one of the Bell-type incoherence inequalities for the correlation tensor components is always violated and, thus, spin correlations of the electron and positron in this process have the strongly pronounced quantum character. Analogous consideration can be wholly applied as well to the two-photon processes γγ → μ+μ- and γγ → τ+τ-, which become possible at considerably higher energies.

Two-photon excitation microscopy in cellular biophysics

1995 ◽  
Vol 53 ◽  
pp. 62-63
Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers
Keyword(s):  
Confocal Microscopy ◽  
Laser Beam ◽  
Duty Cycle ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation 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 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

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