Pump-Probe Photoelectron Spectra

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

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Density matrix and rate equation analyses for picosecond pump/probe combustion diagnostics

AIAA Journal ◽

10.2514/3.14233 ◽

1999 ◽

Vol 37 ◽

pp. 723-731

Author(s):

Thomas Settersten ◽

Mark Linne ◽

James Gord ◽

Gregory Feichtner

Keyword(s):

Density Matrix ◽

Rate Equation ◽

Pump Probe ◽

Combustion Diagnostics

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Two-Dimensional Infrared Spectroscopy From the Gas to Liquid Phase: Density Dependent J-Scrambling, Vibrational Relaxation, and the Onset of Liquid Character

10.26434/chemrxiv.9700427 ◽

2019 ◽

Author(s):

Greg Ng Pack ◽

Matthew Rotondaro ◽

Parth Shah ◽

Aritra Mandal ◽

Shyamsunder Erramilli ◽

...

Keyword(s):

Vibrational Energy ◽

Rotational Relaxation ◽

Vibrational Energy Relaxation ◽

Pump Probe ◽

Solution Dynamics ◽

Supercritical Phase ◽

Supercritical Solution ◽

Asymmetric Stretch ◽

Two Dimensional Infrared Spectroscopy ◽

Vibrational Equilibrium

Ultrafast 2DIR spectra and pump-probe responses of the N2O n 3 asymmetric stretch in SF6 as a function of density from the gas to supercritical phase and liquid are reported. 2DIR spectra unequivocally reveal free rotor character at all densities studied in the gas and supercritical region. Analysis of the 2DIR spectra determines that J-scrambling or rotational relaxation in N2O is highly efficient, occurring in ~1.5 to ~2 collisions with SF6 at all non-liquid densities. In contrast, N2O n 3 vibrational energy relaxation requires ~15 collisions, and complete vibrational equilibrium occurs on the ~ns scale at all densities. An independent binary collision model is sufficient to describe these supercritical state point dynamics. The N2O n 3 in liquid SF6 2DIR spectrum shows no evidence of free rotor character or spectral diffusion. Using these 2DIR results, hindered rotor or liquid-like character is found in gas and all supercritical solutions for SF6 densities ³ r * = 0.3, and increases with SF6 density. 2DIR spectral analysis offers direct time domain evidence of critical slowing for SF6 solutions closest to the critical point density. Applications of 2DIR to other high density and supercritical solution dynamics and descriptions are discussed. <br>

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Strong coupling: resonant effects

10.1093/oso/9780198782995.003.0007 ◽

2017 ◽

Author(s):

Alexey V. Kavokin ◽

Jeremy J. Baumberg ◽

Guillaume Malpuech ◽

Fabrice P. Laussy

Keyword(s):

Strong Coupling ◽

Experimental Studies ◽

Strong Coupling Regime ◽

Theoretical Studies ◽

Stimulated Scattering ◽

Quantum Theories ◽

Pump Probe ◽

Exciton Polaritons ◽

Linear Optical Properties ◽

Experimental And Theoretical Studies

This chapter presents experimental studies performed on planar semiconductor microcavities in the strong-coupling regime. The first section reviews linear experiments performed in the 1990s that evidence the linear optical properties of cavity exciton-polaritons. The chapter is then focused on experimental and theoretical studies of resonantly excited microcavity emission. We mainly describe experimental configuations in which stimulated scattering was observed due to formation of a dynamical condensate of polaritons. Pump-probe and cw experiments are described in addition. Dressing of the polariton dispersion and bistability of the polariton system due to inter-condensate interactions are discussed. The semiclassical and the quantum theories of these effects are presented and their results analysed. The potential for realization of devices is also discussed.

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