Picosecond time-resolved four-wave mixing experiments in sodium-seeded flames

Fourkas, John T.; Brewer, Timothy R.; Kim, Hackjin; Fayer, M. D.

doi:10.1364/ol.16.000177

Cited by 18 publications

(5 citation statements)

References 11 publications

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“…12,29 The TG experiment can, in general, be described by four double-sided Feynman diagrams. 31 -37 Each four-wave mixing Feynman diagram corresponds to a three-dimensional integral containing material transition dipole matrix elements, each of the laser electric fields, and propagator terms that describe the evolution of the system.…”

Section: Theoretical Resultsmentioning

confidence: 99%

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Picosecond polarization-selective transient grating experiments in sodium-seeded flames

Fourkas

Brewer

Kim

et al. 1991

The Journal of Chemical Physics

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The grating decomposition method: A new approach for understanding polarizationselective transient grating experiments. I. Theory J. Chem. Phys. 97, 69 (1992); 10.1063/1.463565 The grating decomposition method: A new approach for understanding polarizationselective transient grating experiments. II. Applications J. Chem. Phys. 97, 78 (1992); 10.1063/1.463525 Analysis of complex molecular dynamics in an organic liquid by polarization selective subpicosecond transient grating experimentsPolarization-selective transient grating experiments have been used to study the subnanosecond time scale dynamics of several sodium-seeded, premixed flames. Intensity gratings (in which both excitation beams are of the same polarization) were used to determine excited-state quenching collision rates, while polarization gratings (in which the excitation beams are cross polarized) were used to measure Na diffusion constants and the rates ofNa ground state magnetic sublevel population scattering collisions. In addition, the rates of scattering between the 3Pl/2 and 3P 312 excited state levels were measured using an excited state probing scheme.is constant across each fringe, whereas the polarization changes from rcp to linear at -45' to Jcp to linear at + 45'.

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Section: Theoretical Resultsmentioning

confidence: 99%

“…We have reported the preliminary results of picosecond, polarization-selective TG studies of sodium atom dynamics in a Na-seeded, premixed, methane/air fiame. 12 Here we present detailed results of our studies of several premixed flames.…”

Section: Introductionmentioning

confidence: 99%

Picosecond polarization-selective transient grating experiments in sodium-seeded flames

Fourkas

Brewer

Kim

et al. 1991

The Journal of Chemical Physics

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“…Fourkas et al [39] recently determined the electronic quenching rate and ground-state dephasing rate from measured grating decay times for sodium seeded into a methane-air flame. [10].…”

Section: Temporal Evolution Of the Density-matrix Elementsmentioning

confidence: 99%

Resonant multiwave-mixing spectra of gas-phase sodium: Nonperturbative calculations

1992

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We perform nonperturbative calculations of resonant multiwave mixing of two high-intensity laser beams of different frequencies both for a general three-level system and for the 3 Siy2 -3 Piy2 electronic resonance of the sodium atom. Our calculations proceed by direct numerical integration of the densitymatrix equations and subsequent Fourier analysis of the calculated time-dependent density-matrix elements. We examine the case where two nearly degenerate input beams are each detuned many collisional linewidths from electronic resonance, and the frequency difference between the input beams is tuned through a ground-state resonance. Unlike previous high-intensity analyses, each input beam can be resonant with numerous transitions simultaneously; for a three-level system, we refer to this as an "M-type" system, in analogy with Aand V-type systems. Calculated four-, six-, and eight-wave-mixing spectra exhibit subharmouic resonances of the type observed experimentally by Trebino and Rahu [Opt. Lett. 12, 912 (1987)]. The three-level system is studied to gain insight into the physics of these subharmouic resonances. For more quantitative comparison with experiment, we use a model that includes the 16 Zeeman and hyper5ne states in the 3 S&~2 and the 3 P&&2 levels, and accounts for arbitrary linear polarization of the input laser radiation. The relative intensities of the resonance features in the calculated multiwave-mixing spectra show good agreement with experiment. These resonance features broaden and shift as laser intensity increases, as predicted for four-wave-mixing processes in previous, less general high-intensity analyses. Both theory and experiment also show additional resonant features in the eight-wave-mixing spectra that appear at very high intensity.

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“…where (1/2ikxT)exp(ikxTlx -x'I) is the Green function of Eq. (11). We determine the amplitudes of the transmitted and reflected diffracted waves, denoted aT and aR, respectively, by matching the boundary conditions for the tangential components of the electric and magnetic fields, which reduce again to the continuity of ul and du,/dx at x = 0.…”

Section: Theorymentioning

confidence: 99%

Surface selectivity in four-wave mixing: transient gratings as a theoretical and experimental example

et al. 1991

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A theoretical treatment of transient grating diffraction is derived for gratings that are spatially nonuniform in the direction perpendicular to the sample surface. This treatment is readily generalized to any four-wave mixing experiment. Both reflection and transmission geometries of diffraction are examined for the standard transient grating case, in which both grating excitation beams are incident upon the same side of the sample. For samples in which the grating amplitude perpendicular to the sample surface varies slowly relative to the optical wavelength, the reflection geometry is shown to probe only the surface or the interface, while the transmission geometry probes the bulk of the sample. An experimental example using four transient grating geometries (two reflection, two transmission) is shown to yield significantly different temporal responses, illustrating the nature of the theoretical predictions. The sample is a thin molecular crystal upon a substrate. Both electronic excitations (excitons) and wave-guided acoustic modes are generated and probed. Distinct signals are obtained from the bulk, the crystal-substrate interface, and the free-crystal face. Model calculations are presented that illuminate the behavior of the experimental example.

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Picosecond time-resolved four-wave mixing experiments in sodium-seeded flames

Cited by 18 publications

References 11 publications

Picosecond polarization-selective transient grating experiments in sodium-seeded flames

Picosecond polarization-selective transient grating experiments in sodium-seeded flames

Resonant multiwave-mixing spectra of gas-phase sodium: Nonperturbative calculations

Surface selectivity in four-wave mixing: transient gratings as a theoretical and experimental example

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