Two‐photon spectrometer based on flashlamp‐pumped dye lasers

1977 ◽  
Vol 48 (11) ◽  
pp. 1436-1439 ◽  
Author(s):  
V. SethuRaman ◽  
G. J. Small ◽  
E. S. Yeung
Keyword(s):  
Dye Lasers ◽  
Two Photon

Doppler-free two-photon transitions to Rydberg levels: convenient, useful, and precise reference wavelengths for dye lasers

1978 ◽  
Vol 3 (4) ◽  
pp. 141 ◽  
Author(s):  
S. A. Lee ◽  
B. P. Stoicheff ◽  
J. Helmcke ◽  
J. L. Hall
Keyword(s):  
Dye Lasers ◽  
Two Photon

Two-photon spectroscopy utilizing dye lasers

1972 ◽  
Vol 15 (3) ◽  
pp. 309-315 ◽  
Author(s):  
Amalia Bergman ◽  
Joshua Jortner
Keyword(s):  
Dye Lasers ◽  
Two Photon

Molecular two-photon spectroscopy with two synchronized tunable dye lasers

1977 ◽  
Vol 46 (3) ◽  
pp. 406-410 ◽  
Author(s):  
W. Hampf ◽  
H.J. Neusser ◽  
E.W. Schlag
Keyword(s):  
Dye Lasers ◽  
Two Photon

Titanium: Sapphire Laser as an Excitation Source in Two-Photon Spectroscopy

1997 ◽  
Vol 51 (2) ◽  
pp. 218-226 ◽  
Author(s):  
W. G. Fisher ◽  
E. A. Wachter ◽  
Michael Armas ◽  
Colin Seaton
Keyword(s):  
Near Infrared ◽  
Average Power ◽  
Sapphire Laser ◽  
Excitation Source ◽  
Dye Lasers ◽  
Titanium:Sapphire Laser ◽  
Excitation Spectra ◽  
Two Photon ◽  
Double Beam ◽  
Synchronously Pumped

The passively mode-locked titanium: sapphire laser provides new opportunities for acquiring two-photon spectral data in the near-infrared, a region not commonly accessible to synchronously pumped dye lasers. This source generates pulses with peak powers near 100 kW at average powers over 1 W and is capable of yielding two-photon signals roughly two orders of magnitude larger than is possible with synchronously pumped dye lasers. However, the multimode output of this laser exhibits significant temporal and spectral pulse profile variations as the laser wavelength is tuned. As a consequence, peak powers of the titanium:sapphire laser can vary independently from average power across the tuning range. This wavelength dependence, coupled with the quadratic dependence of the two-photon signal upon the instantaneous power of the laser, precludes simple average power correction of nonlinear spectral band shapes. Here, we investigate the key properties of the titanium:sapphire laser as an excitation source for two-photon spectroscopy. We also identify a chemical reference suitable for obtaining source-corrected excitation spectra in the near-infrared using a double-beam, ratiometric approach; this is based on a source-in-dependent two-photon excitation spectrum for the laser dye coumarin-480 that has been obtained with a single-frequency titanium:sapphire laser. From these data, correction factors are generated for correction of multimode source data.

scholarly journals Laser-induced plasmas in metal vapors

1989 ◽  
Vol 7 (3) ◽  
pp. 545-550 ◽  
Author(s):  
J. T. Bahns ◽  
M. Koch ◽  
W. C. Stwalley
Keyword(s):  
Low Power ◽  
Dye Laser ◽  
Experimental Results ◽  
Resonance Ionization ◽  
Dye Lasers ◽  
High Electron ◽  
Two Photon ◽  
Cw Laser ◽  
Metal Vapors ◽  
Photon Resonance

Strong ionization in metal vapors is known to be very readily produced by a variety of pulsed and CW lasers. Particularly well known is ‘resonance’ ionization by pulsed or CW dye lasers operated at the atomic resonance lines (e.g. Na 3s → 3p). We also have experimental results for two other forms of ionization: ‘quasiresonant’ ionization using a CW dye laser (e.g. at the Na 3p → 4d transitions), and ‘two-photon resonance’ ionization using a pulsed dye laser (e.g. at the Na 3s → 4d two-photon resonances). Both new forms are visually characterized by bright ‘white sparks’ and correspond to reasonably high electron densities of ∼1014−1015 cm3 and low electron temperatures of ∼0·1−0·2 eV. The ‘quasiresonant’ ionization is remarkable in that it occurs even with a very low power 1 mW focused CW laser in 10 torr of Na. A variety of interesting atomic and molecular spectroscopic features have been observed and analyzed.

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.

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