Stepwise Two-Photon Excitation of Tetracene; Fluorescence from Upper Excited Singlet States

1977 ◽  
Vol 81 (3) ◽  
pp. 281-285 ◽  
Author(s):  
Bernhard Nickel ◽  
Gabriele Roden
Keyword(s):  
Excited Singlet ◽  
Two Photon ◽  
Photon Excitation ◽  
Singlet States ◽  
Excited Singlet States ◽  
Two Photon Excitation

Low-lying singlet states in the two-photon excitation spectrum of chrysene

1989 ◽  
Vol 164 (2-3) ◽  
pp. 313-319 ◽  
Author(s):  
N.Q. Liem ◽  
P.R. Salvi ◽  
G. Marconi ◽  
N. Orlić
Keyword(s):  
Excitation Spectrum ◽  
Two Photon ◽  
Photon Excitation ◽  
Singlet States ◽  
Two Photon Excitation

Two-Photon Study on the Electronic Interactions between the First Excited Singlet States in Carotenoid−Tetrapyrrole Dyads

2011 ◽  
Vol 115 (16) ◽  
pp. 4082-4091 ◽  
Author(s):  
Pen-Nan Liao ◽  
Smitha Pillai ◽  
Devens Gust ◽  
Thomas A. Moore ◽  
Ana L. Moore ◽  
...  
Keyword(s):  
Excited Singlet ◽  
Electronic Interactions ◽  
Two Photon ◽  
Singlet States ◽  
Excited Singlet States

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.

Two-photon excitation fluorescence microscopy in living systems

1993 ◽  
Vol 51 ◽  
pp. 154-155 ◽  
Author(s):  
David W. Piston
Keyword(s):  
Confocal Microscopy ◽  
Fluorescence Microscopy ◽  
Singlet State ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. 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 our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. 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.

Two‐photon excitation fluorescence microscopy using a semiconductor laser

Bioimaging ◽  
1995 ◽  
Vol 3 (2) ◽  
pp. 70-75 ◽  
Author(s):  
Pekka E Hänninen ◽  
Martin Schrader ◽  
Erkki Soini ◽  
Stefan W Hell
Keyword(s):  
Fluorescence Microscopy ◽  
Semiconductor Laser ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation
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