scholarly journals Photoselection of Luminescent Molecules in Anisotropic Media in the Case of Two-Photon Excitation. Part II. Experimental Studies of Hoechst 33342 in Stretched Polyvinyl alcohol) Films

1996 ◽  
Vol 51 (9) ◽  
pp. 1037-1041 ◽  
Author(s):  
A. Kawski ◽  
Z. Gryczyński ◽  
I. Gryczyński ◽  
J. R. Lakowicz ◽  
G. Piszczek
Keyword(s):  
Polyvinyl Alcohol ◽  
Vinyl Alcohol ◽  
Experimental Studies ◽  
Poly Vinyl Alcohol ◽  
Hoechst 33342 ◽  
Emission Anisotropy ◽  
Two Photon ◽  
Photon Excitation ◽  
Polyvinyl Alcohol Films ◽  
Two Photon Excitation

Abstract It was found by investigating dichroism and emission anisotropy in the case of one-and two-photon excitation of Hoechst 33342 [bis-benzimide,2,5'-bi-1H-benzimidazole, 2'-(4-ethoxyphenyl)-5-5(4-methyl-1-piperazinyl)] in stretched poly(vinyl alcohol) (PVA) films, that the absorption and fluorescence transition moments lie along the long molecular axis of the molecule studied. The slight deviation of the transition moment direction in fluorescence (about 8°) from that in absorption can be due to the incomplete linearity of the Hoechst molecule.

Substituent Effects on the Luminescence of 2-Substituted 3-Methylquinoxalines in Poly (Vinyl Alcohol) Films*

1991 ◽  
Vol 46 (4) ◽  
pp. 304-306 ◽  
Author(s):  
Z. Gryczyński ◽  
A. Kawski
Keyword(s):  
Polyvinyl Alcohol ◽  
Temperature Dependence ◽  
Vinyl Alcohol ◽  
Substituent Effects ◽  
Quantum Yields ◽  
Poly Vinyl Alcohol ◽  
Band Position ◽  
Fluorescence And Phosphorescence ◽  
Polyvinyl Alcohol Films

Abstract The effect of 2-substitutions (NH2 . O, CH3O, CI. Br) in 3-methylquinoxalines on the fluorescence and phosphorescence band position and intensity at 293 K, and the temperature dependence of their fluorescence and phosphorescence quantum yields were investigated in polyvinyl alcohol) films

Photoluminescence Properties of trans–4,4'–Diamino–stilbene in Poly(vinyl alcohol) Films

1996 ◽  
Vol 51 (10-11) ◽  
pp. 1153-1156 ◽  
Author(s):  
A. Kawski ◽  
A. Kubicki ◽  
B. Kukliński ◽  
T. Nowosielski
Keyword(s):  
Vinyl Alcohol ◽  
Experimental Studies ◽  
Poly Vinyl Alcohol ◽  
Photoluminescence Properties ◽  
Emission Anisotropy ◽  
Distinct Effect ◽  
Unusual Behaviour ◽  
Nonpolar Molecule ◽  
Direct Irradiation ◽  
Fluorescence And Phosphorescence

Abstract Experimental studies have shown that the nonpolar molecule 4,4'-diamino-stilbene (DAS) in poly(vinyl alcohol) film (PVA) at 296 K, apart from fluorescence displays phosphorescence whose intensity differs only slightly from that observed at 84 K. The overlapping of fluorescence and phosphorescence bands is the reason of the unusual behaviour of the emission anisotropy in the longwave absorption and photoluminescence bands. A distinct effect of direct irradiation on the intensity of these bands was observed.

Unusual Absorption and Fluorescence Properties of p-Substituted Stilbenes in Poly (vinyl alcohol) Films

1995 ◽  
Vol 50 (12) ◽  
pp. 1170-1174
Author(s):  
A. Kawski ◽  
B. Kukliński ◽  
T. Nowosielski
Keyword(s):  
Double Bond ◽  
Polyvinyl Alcohol ◽  
Vinyl Alcohol ◽  
Fluorescence Properties ◽  
Poly Vinyl Alcohol ◽  
Emission Anisotropy ◽  
Unusual Behaviour ◽  
Different Temperatures ◽  
Linear Polyenes ◽  
Linear Molecules

Abstract The behaviour of absorbance, fluorescence and emission anisotropy of linear molecules with one double bond, i.e. 4-amino-4'-nitrostilbene (ANS), 4-dimethylamino-4'-nitrostilbene (DNS) and 4,4'-diphenylstilbene (DPS), was examined in polyvinyl alcohol) (PVA) films at different temperatures (293-423 K). The unusual behaviour of absorption and fluorescence properties of the molecules in­ vestigated, similar to those of linear polyenes in PVA, was, however, less pronounced.

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

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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