Wojciech J Gadomski | University of Warsaw (original) (raw)
physicist at University of Warsaw, head of research group "femto.chem.uw.edu.pl"
Phone: 501487952
Address: Zwirki i Wigury 101
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Papers by Wojciech J Gadomski
Photon Correlation & Scattering
In recent years the spectroscopic investigations of the probe molecules in heteroclusters have be... more In recent years the spectroscopic investigations of the probe molecules in heteroclusters have become widely applied method for studying the dynamic size effects in clusters.1 Herewith we consider the process of gelation of agueous gelatin solution, which can be analysed in terms of growing clusters of gelatin molecules connected by intermolecular hydrogen bonds2. The sol- gel transition is investigated by detection of the fluorescence yield of probe dye molecules conjugated to the gelatin coils. We prove experimentally and theoretically that the time evolution of the dye fluorescence spectrum reflects the kinetics of helix formation in this process.
Annual Meeting Optical Society of America
Unstable and bistable behavior has been predicted recently in multimode homogeneously broadened l... more Unstable and bistable behavior has been predicted recently in multimode homogeneously broadened lasers as a function of the detuning between the cavity and the atomic frequencies. As an example of a device for which most required physical conditions for the appearance of this instability are satisfied, we have analyzed the behavior of a low-pressure (10–20 Torr) CO2 laser. The operating parameters (relaxation rates for the population inversion, 104s−1, and for the polarization, 108s−1) restrict the accessible range of theoretically expected phenomena to a stable intensity output without evidence of stable self-pulsing. However, mode–mode competition is responsible for bistability in both the intensity and the operating frequency on varying the detuning parameter. This behavior is confirmed by additional observations of the transient that accompanies the jump between the two stable branches. We have also studied the effect of varying the cavity losses and discovered bistability also ...
The amplitude of the overtone, parametrically generated in a crystal lattice with a slowly varyin... more The amplitude of the overtone, parametrically generated in a crystal lattice with a slowly varying envelope, is shown to exhibit bistability and a period doubling route to chaos.
By using an embedding technique [1] in both time series and stroboscopic sections of the output i... more By using an embedding technique [1] in both time series and stroboscopic sections of the output intensity of a CO2 laser with modulated losses [2], we perform dimensionality tests on periodic and aperiodic attractors. Measurements at the accumulation point of the Feigenbaum cascade and inside the chaotic region (Fig. 1) confirms previous results of the general theory on non-linear dynamics.
Recently2 it has been shown that certain dynamical behaviors of a single mode CO2 laser cannot be... more Recently2 it has been shown that certain dynamical behaviors of a single mode CO2 laser cannot be explained by the two-level model of a molecular laser. The alternative four-level model, in which the two active resonant levels of a CO2 molecule are strongly coupled with the other rotational levels of the vibrational bands,3 gives significantly better agreement with the experiment.2 Although this model introduces at least three degrees of freedom, a large class of phenomena, such as the dynamics of Q-switching, external sinusoidal modulation or external feedback,4 suggests that only two dynamical variables are relevant. It yields that this problem could be reduced to two dimensions.
... Zwirki i Wigury 101, PL-02-089 Warsaw, Poland I. NEDKOV Institute of Electronics, Bulgarian A... more ... Zwirki i Wigury 101, PL-02-089 Warsaw, Poland I. NEDKOV Institute of Electronics, Bulgarian Academy of Sciences, Tzarigrazdsko Chaussee Boulevard 72 1784 Sofia, Bulgaria AND H. BOUGRINE AND M. AUSLOOS SUPRAS, Institute of ... EA Jagla and CA Balseiro, Phys. Rev. ...
The Journal of Chemical Physics, 2014
We have studied the effect of transient vibrational inversion of population in trans-β-apo-8′-car... more We have studied the effect of transient vibrational inversion of population in trans-β-apo-8′-carotenal on the time-resolved femtosecond stimulated Raman scattering (TR-FSRS) signal. The experimental data are interpreted by applying a quantum mechanical approach, using the formalism of projection operators for constructing the theoretical model of TR-FSRS. Within this theoretical frame we explain the presence of transient Raman losses on the Stokes side of the TR-FSRS spectrum as the effect of vibrational inversion of population. In view of the obtained experimental and theoretical results, we conclude that the excited S2 electronic level of trans-β-apo-8′-carotenal relaxes towards the S0 ground state through a set of four vibrational sublevels of S1 state.
Photon Correlation & Scattering
In recent years the spectroscopic investigations of the probe molecules in heteroclusters have be... more In recent years the spectroscopic investigations of the probe molecules in heteroclusters have become widely applied method for studying the dynamic size effects in clusters.1 Herewith we consider the process of gelation of agueous gelatin solution, which can be analysed in terms of growing clusters of gelatin molecules connected by intermolecular hydrogen bonds2. The sol- gel transition is investigated by detection of the fluorescence yield of probe dye molecules conjugated to the gelatin coils. We prove experimentally and theoretically that the time evolution of the dye fluorescence spectrum reflects the kinetics of helix formation in this process.
Annual Meeting Optical Society of America
Unstable and bistable behavior has been predicted recently in multimode homogeneously broadened l... more Unstable and bistable behavior has been predicted recently in multimode homogeneously broadened lasers as a function of the detuning between the cavity and the atomic frequencies. As an example of a device for which most required physical conditions for the appearance of this instability are satisfied, we have analyzed the behavior of a low-pressure (10–20 Torr) CO2 laser. The operating parameters (relaxation rates for the population inversion, 104s−1, and for the polarization, 108s−1) restrict the accessible range of theoretically expected phenomena to a stable intensity output without evidence of stable self-pulsing. However, mode–mode competition is responsible for bistability in both the intensity and the operating frequency on varying the detuning parameter. This behavior is confirmed by additional observations of the transient that accompanies the jump between the two stable branches. We have also studied the effect of varying the cavity losses and discovered bistability also ...
The amplitude of the overtone, parametrically generated in a crystal lattice with a slowly varyin... more The amplitude of the overtone, parametrically generated in a crystal lattice with a slowly varying envelope, is shown to exhibit bistability and a period doubling route to chaos.
By using an embedding technique [1] in both time series and stroboscopic sections of the output i... more By using an embedding technique [1] in both time series and stroboscopic sections of the output intensity of a CO2 laser with modulated losses [2], we perform dimensionality tests on periodic and aperiodic attractors. Measurements at the accumulation point of the Feigenbaum cascade and inside the chaotic region (Fig. 1) confirms previous results of the general theory on non-linear dynamics.
Recently2 it has been shown that certain dynamical behaviors of a single mode CO2 laser cannot be... more Recently2 it has been shown that certain dynamical behaviors of a single mode CO2 laser cannot be explained by the two-level model of a molecular laser. The alternative four-level model, in which the two active resonant levels of a CO2 molecule are strongly coupled with the other rotational levels of the vibrational bands,3 gives significantly better agreement with the experiment.2 Although this model introduces at least three degrees of freedom, a large class of phenomena, such as the dynamics of Q-switching, external sinusoidal modulation or external feedback,4 suggests that only two dynamical variables are relevant. It yields that this problem could be reduced to two dimensions.
... Zwirki i Wigury 101, PL-02-089 Warsaw, Poland I. NEDKOV Institute of Electronics, Bulgarian A... more ... Zwirki i Wigury 101, PL-02-089 Warsaw, Poland I. NEDKOV Institute of Electronics, Bulgarian Academy of Sciences, Tzarigrazdsko Chaussee Boulevard 72 1784 Sofia, Bulgaria AND H. BOUGRINE AND M. AUSLOOS SUPRAS, Institute of ... EA Jagla and CA Balseiro, Phys. Rev. ...
The Journal of Chemical Physics, 2014
We have studied the effect of transient vibrational inversion of population in trans-β-apo-8′-car... more We have studied the effect of transient vibrational inversion of population in trans-β-apo-8′-carotenal on the time-resolved femtosecond stimulated Raman scattering (TR-FSRS) signal. The experimental data are interpreted by applying a quantum mechanical approach, using the formalism of projection operators for constructing the theoretical model of TR-FSRS. Within this theoretical frame we explain the presence of transient Raman losses on the Stokes side of the TR-FSRS spectrum as the effect of vibrational inversion of population. In view of the obtained experimental and theoretical results, we conclude that the excited S2 electronic level of trans-β-apo-8′-carotenal relaxes towards the S0 ground state through a set of four vibrational sublevels of S1 state.