Gas Phase Two-Photon Spectroscopy of Polyazines: Pyrazine

1979 ◽  
Vol 34 (8) ◽  
pp. 979-982 ◽  
Author(s):  
I. Knoth ◽  
H. J. Neusser ◽  
E. W. Schlag
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Vibrational Frequencies ◽  
Photon Absorption ◽  
Excitation Spectra ◽  
Selection Rules ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Abstract The two-photon excitation spectra of gas phase pyrazine-h4 and -d 4 in the region of the S1←S0 transition are presented. The two-photon absorption which is electronically forbidden is induced by-various vibrations of ungerade parity. Because of the different selection rules for two-photon transitions hitherto unknown vibrational frequencies in the excited state 1B3u have been determined.

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.

Broadband Excited State Dynamics of Common Reverse Saturable Absorbing Dye Media.

1994 ◽  
Vol 374 ◽  
Author(s):  
Kenneth J. McEwan ◽  
Richard C. Hollins
Keyword(s):  
Excited State ◽  
Organic Liquid ◽  
Excited State Absorption ◽  
Photon Absorption ◽  
Excited State Lifetime ◽  
Absorption And Emission ◽  
Two Photon Absorption ◽  
Two Photon ◽  
State Response ◽  
Photon Excitation

AbstractIn this paper we describe a technique by which the broadband excited state absorption/emission and dynamics can be measured for materials with either linear or two photon absorption. The technique is applied to two different dyes in solution and to a cyano-biphenyl organic liquid. The ratio of σex/σgr for HITCI in methanol is greater than 1 from 400 to 570nm and at 532nn is determined to be 25; the excited state lifetime is 800ps. For CAP in methanol σex/σgr is greater than 1 from 400–650nm and is 14 at 532nm. Dimer absorption and emission are found to contribute to the excited state response in this material. In the organic liquid broadband (400–570nm) excited state absorption is measured following two photon excitation at 588nm.

scholarly journals Phenothiazin-N-yl-capped 1,4-diketo-3,6-diphenylpyrrolo[3,4-c]pyrrole exhibiting strong two-photon absorption and aggregation-enhanced one- and two-photon excitation red fluorescence

RSC Advances ◽  
2017 ◽  
Vol 7 (49) ◽  
pp. 30610-30617 ◽  
Author(s):  
Kai Zhang ◽  
Zhongwei Liu ◽  
Shian Ying ◽  
Mingshuai Chen ◽  
Shanfeng Xue ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Two Photon Absorption ◽  
Red Fluorescence ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

A phenothiazin-capped simple DPP dye exhibits a large two-photon absorption cross section and aggregation-enhanced one- and two-photon excitation red fluorescence.

Quantitative Imaging of Metabolism by Two-Photon Excitation Microscopy

1999 ◽  
Vol 5 (S2) ◽  
pp. 1048-1049
Author(s):  
David W. Piston ◽  
Susan Knobel ◽  
George Patterson
Keyword(s):  
Quantitative Imaging ◽  
Photon Absorption ◽  
Limiting Factors ◽  
Focal Volume ◽  
Time Resolved ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Small Absorption ◽  
Two Photon Excitation

Two-photon excitation microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Because of the intensity-squared dependence of the two-photon absorption, the excitation is limited to the focal volume. This inherent localization minimizes photobleaching and photodamage - the ultimate limiting factors in fluorescence microscopy of living cells. One of the most powerful applications of two-photon excitation microscopy is imaging from the naturally occurring reduced pyridine nucleotides (NAD(P)H). NAD(P)H is a useful indicator of cellular metabolism, but it is not a “good“ fluorophore (it has a small absorption cross-section and a low quantum yield). Two-photon excitation of NAD(P)H yields minimal photodamage, thus allowing time-resolved threedimensional metabolic mapping of cellular redox state. We have used two-photon excitation microscopy to examine glucose metabolism in pancreatic and muscle cells. As glucose is metabolized by these cells, intermediate metabolism results in an increase in the reduced-tooxidized NAD(P)H/NAD(P)+ ratio, and a concomitant increase in autofluorescence.

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.

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