J. Krasiński

Experimental dependence of two-photon absorption efficiency on statistical properties of laser light

Abstract The fluorescence intensity excited by two-photon absorption of the 514.5 nm argon laser line has been investigated for various oxasol derivatives. The fluorescence intensity was dependent on the statistical properties of the 514.5 nm argon laser line and was a factor 1.52-1.86 larger for absorption of a multifrequency laser line than in the case of a single frequency laser line.

Time behaviour of diffuse band emission in Na2 and K2

Abstract The C states of sodium and potassium dimers were excited with short laser pulses (about 500 ps) and time evolution of the diffuse bands in Na2 (413–456 nm) and K2 (550–583 nm) was observed in fluorescence. The measured decay times were interpreted as lifetimes of unidentified triplet states giving origin to the diffuse bands. Our results contradict the values reported before.

The process of energy transfer between excited sodium atoms

Abstract Two experiments were carried out to test a process proposed by Allegrini et al. as a viable explanation of the fluorescence from high lying levels which is observed when sodium vapor is illuminated by resonance radiation. In the first experiment a cell with sodium vapor was illuminated by a cw dye laser tuned to the 3S → 3P transition, and the linewidth and lineshape of the fluorescence from the 3D → 3P transition were measured. In the second experiment the cell was illuminated by two pulsed lasers, one tuned to the 3S → 3P resonance and the second well off resonance with this transition. The photoionization current was measured, as was the fluorescence intensity from the 6S → 3P and 5D → 3P transitions. We conclude that the Allegrini process does not significantly contribute to the populations in the 5D, 6S and 3D states.

Influence of nonlinear effects on the statistical properties of a high power density laser beam

Abstract The second-order intensity correlation function g(2)(0) of a laser beam passing through a nonlinear medium has been experimentally found to be a decreasing function of the power density in the medium.

Investigations of ionization of sodium vapour by resonant laser light

Abstract The ionization of dense sodium vapour in presence of various buffer gases by high power density light tuned to 3S → 3P transition was investigated. The by Measures proposed process of impact ionization by electrons heated in superelastic collisions was considered to be predominant. It was found, that the decrease of the ionization rate by a high pressure noble gas takes place due to the shortening of the effective lifetime of 3P-excited sodium atoms or due to formation of sodium-noble gas quasimolecules. The decrease of the time of imprisonment of the resonance radiation with the increase of the electron density was observed.

A note on the dispersion of a prism used as a beam expander in a nitrogen laser pumped dye laser

Abstract It is shown that the dispersion of the prism material in a grating tuned dye laser containing an intracavity prism beam expander cannot be neglected in practical situations.

Laser properties of fluorescent brightening agents

Abstract The laser properties of 19 dyes commonly used as fluorescent brightening agents (FBA) have been studied. A nitrogen laser served as the pumping source. The absorption spectra and the relationship between laser power and wavelength was determined for these dyes. Since several of these compounds have an efficiency comparable to that of the POPOP scintillator commonly used in this part of the spectrum, and since they are easily soluble in alcohols and furthermore, are very inexpensive, they may be competitive with other dyes hitherto used in the violet-blue region.

Investigation of the two-photon absorption spectrum of 3,4-benzopyrene by means of a tunable dye laser

Abstract The two-photon absorption of the solid solution of 3,4-benzopyrene in methyl polymetacrylate, induced by a tunable dye laser has been investigated. An absorption spectrum in the range of 530–750 nm has been obtained. The dependence of the fluorescence intensity IF upon the laser power IF, IFλIkL and the relation k=k(λ) has been i investigated.

An improved automatically tunable second harmonic generation of dye laser

Abstract A simple compact and high efficiency automatic frequency doubling system is described.

Dependence of two-photon absorption efficiency on the relative intensities of two modes simultaneously generated by a cw laser

Abstract The two-photon absorption induced by a cw argon laser has been investigated. The efficiency of this process has experimentally been found to depend on the relative intensities of two modes simulataneously generated by the laser. Good agreement with presented theoretical predictions has been established.