Photon Echo Experiments Research Articles

Non-Markovian Dynamics of the Vibrations of Ions in Water from Femtosecond Infrared Three-Pulse Photon Echoes

The first femtosecond three-pulse photon echo experiment of a vibrational transition is presented. A mode of the azide ion ${\mathrm{N}}_{3}^{\ensuremath{-}}$ at $2043{\mathrm{cm}}^{\ensuremath{-}1}$ is used to probe the impulsively excited vibrational energy distribution and hence the dynamics of the water around the ion. The vibrational frequency correlations decay on time scales of about 80 fs and 1.3 ps, while a small part remains for longer than about 10 ps. The 1.3 ps decay is the residence time for hydrogen bonds to the ion. Major differences between vibrational and optical three-pulse echoes are addressed.

Optical Dephasing of Eu 3+ in Yttrium Oxide Crystals

Optical dephasing in a number of crystalline samples of Y 2 O 3 : Eu 3+ prepared by two different crystal-growth techniques were measured using two pulse photon echo method. For crystals prepared by a laser-heated pedestal growth, we report the dephasing rate, 1/ T m , at 1.4 K is up to two orders of magnitude faster than that previuosly reported for the flame fusion growth crystal. The spatial dependence of the optical dephasing rate, measured by TPPE (two-pulse photon echo), tells that the environments of echo producing ions at least highly depend on the spatial position which can not be detected by conventional laser spectroscopy techniques, suggesting two-pulse photon echo experiment can be served as a tool for probing the uniformity of the samples.

Ultrafast Librational Dynamics of the Hydrated Electron

Photon echo and resonant transient grating experiments on the equilibrated aqueous electron are reported, using 15 fs excitation pulses. Both experiments exhibit clear signatures of wave packet dynamics, attributed to an underdamped solvent motion of about $850\mathrm{cm}{}^{\ensuremath{-}1}$. Experiments in ${D}_{2}\mathrm{O}$ expose the librational nature of this mode. The overall agreement between experiment and quantum-molecular dynamics simulations is good, except for the initial oscillatory dynamics, which have not been predicted.

Photon echo experiments on 3–3′ diethylthiacarbocyanine in glass-forming liquids with ultrafast laser pulses

Photon echo experiments on diethylthiacarbocyanine iodide (DTCI) in dibuthylphthalate (DBP) and glycerol in the glass phase with femtosecond pulses are presented. The PE signal shows nonexponential decays even at low temperatures. This behavior is attributed to the many vibronic resonances of the chromophore/ glass system which can be simultaneously excited by the spectral bandwith of the laser pulses. We are able to extract from the PE decays the contribution of the homogeneous dephasing rate of the 0-0 transition of DTCI up to 20 K in dibutylphthalate and 40 K in glycerol. A beating structure in the echo decay for the system DTCI/DBP is also observed from 8 K up to 180 K (glass transition temperature for DBP). This feature is attributed to an intereference process involving excitation of a vibronic transition of DTCI characterized by a vibrational frequency of 300 cm-1.

Nonequilibrium spectral diffusion due to laser heating in stimulated-photon-echo spectroscopy of low-temperature glasses

A quantitative theory is developed, which accounts for heating artifacts in three-pulse photon echo (3PE) experiments. The heat diffusion equation is solved and the average value of the temperature in the focal volume of the laser is determined as a function of the 3PE waiting time. This temperature is used in the framework of nonequilibrium spectral diffusion theory to calculate the effective homogeneous linewidth of an ensemble of probe molecules embedded in an amorphous host. The theory fits recently observed plateaus and bumps without introducing a gap in the distribution function of flip rates of the two-level systems or any other major modification of the standard tunneling model.

Three pulse stimulated photon echo experiments as a probe of polar solvation dynamics: Utility of harmonic bath models

The three pulse photon echo peak shift technique was used to study solvation dynamics in acetonitrile (297 K), methanol (297 and 323 K), and ethylene glycol (297 and 397 K) utilizing the tricarbocyanine laser dye, IR144, as a probe. The spectral density, ρ(ω), governing the solute-solvent interaction was obtained for each solvent and temperature through numerical fitting of the three pulse photon echo peak shift relaxation using finite temporal-duration optical fields. An ultrafast three pulse photon echo peak shift relaxation, ascribed to the inertial component, was nearly identical for ethylene glycol at 297 and 397 K; this indicates the spectral density is essentially temperature independent from 10 to 250 cm−1 over this temperature range. Conversely, the low-frequency spectral density (0–10 cm−1) obtained from three pulse photon echo peak shift relaxation of ethylene glycol at 297 and 397 K showed a strong temperature dependence which cannot be predicted using harmonic bath models. We calculated spectral densities for ethylene glycol, acetonitrile, and methanol using the simple dielectric continuum model and the dynamical mean spherical approximation, using where possible, the relative permittivity constants calculated from experimental far-infrared absorption data and dielectric dispersion data. Additionally, we calculated spectral densities in terms of the extended reference interaction site model for methanol and acetonitrile. These calculated spectral densities describe our experimental methanol and acetonitrile photon echo better than all other solvation model spectral densities. Our results give insight into the domain of applicability of the harmonic model of liquid dynamics.

Accumulated Photon Echo Studies on Bacterial Photosynthetic Reaction Centers: Charge-Transfer Rate Distribution and Electron−Phonon Coupling

The dephasing kinetics of the excitation in the P-870 band of Rb. sphaeroides R26 and the mutant Rb. sphaeroides (M)Y210W was measured by accumulated photon echo experiments. The photon echo signal shows an extremely fast component and a nonexponential longer decay. The fast component is attributed to electron−phonon coupling, and the Huang−Rhys factor is determined to be about S = 1.7. The longer decay components are attributed to charge transfer from the primary donor. The multiple decay components can be explained by assuming dispersive kinetics due to configurational and energetic disorder. The results are compared with those of incoherent pump−probe and hole-burning experiments.

The Energy Landscape of Myoglobin: An Optical Study

In this paper we demonstrate how the potential energy surface of a protein, which determines its conformational degrees of freedom, can be constructed from a series of advanced nonlinear optical experiments. The energy landscape of myoglobin was probed by studying its low-temperature structural dynamics, using several spectral hole burning and photon echo techniques. The spectral diffusion of the heme group of the protein was studied on a time scale ranging from nanoseconds to several days while covering a temperature range from 100 mK to 23 K. The spectral line broadening, as measured in three-pulse stimulated photon echo experiments, occurs in a stepwise fashion, while the exact time dependence of the line width is critically dependent on temperature. From these results we obtained the energy barriers between the conformational states of the protein. Aging time dependent hole-burning experiments show that, at 100 mK, it takes several days for the protein to reach thermal equilibrium. When, after this pe...

Fractal approach to the exciton-phonon coupling and structure of J aggregates

We present a study on exciton-phonon coupling in molecular aggregates at low temperature probed by photon-echo and resonance Raman experiments. A large peak in the low-frequency Raman spectrum is interpreted as a boson peak. Our results for the J aggregates of the dye 5,${5}^{|\mathrm{I}\mathrm{H}}$, 6,${6}^{|\mathrm{I}\mathrm{H}}$-tetrachloro-1,${1}^{|\mathrm{I}\mathrm{H}}$-diethyl-3,${3}^{|\mathrm{I}\mathrm{H}}$-di(4-sulfobutyl)-benzimidazolocarbocyanine indicate an anomalous vibrational density of states with a spectral (or fracton) dimension of 1.44 at 3.9 K. The spectral dimension increases with temperature, suggesting that the topological dimension of the aggregates in solution is 1 and that an increase in temperature leads to an increase in effective branching of the aggregate.

First-, third-, and fifth-order resonant spectroscopy of an anharmonic displaced oscillators system in the condensed phase

We have obtained Nth-order response functions for a two-level system described by displaced anharmonic potential surfaces coupled to a heat bath. The anharmonicity of the potentials has been taken into account as a perturbation of harmonic potentials. The heat-bath was assumed to be an ensemble of harmonic oscillators. Coupling between the two-level system and the bath was assumed to be bilinear. The calculations were done analytically using the Liouville-space generating functional, which had been obtained by way of the path-integral approach. The response functions have been defined in terms of line-shape functions with these line-shape functions being expressed in terms of the bath spectral density and the temperature. We have carried out model calculations of the first-, third-, and fifth-order optical processes for various parameters of anharmonicity to show that anharmonicity plays a minor role in linear absorption, impulsive pump–probe, and photon echo experiments, but plays a major role, in some cases, in fifth-order two-dimensional resonant spectroscopy which is proposed in this paper.

Low temperature optical dephasing in polymethylmethacrylate: A photon echo study below 1 K

The first photon echo experiments on polymethylmethacrylate (PMMA) down to temperatures below 1 K are reported. A linear temperature dependence of the linewidth of the chromophore zinc-meso-tetraphenylporphine (ZnTPP) is obtained below 1 K. Based on this result a flat distribution of two-level system energies E on the time scale of our experiment is deduced. Above 1 K an activated process with an energy of 5 cm−1 is found, which explains the power law dependence usually measured by photon echo experiments in the temperature region 1.2–2.1 K. The fit parameters of the proposed process are shown to be in agreement with hole burning measurements and with specific heat data on PMMA.

Photon-echo novelty filter for measuring a sudden change in index of refraction

An optical novelty filter with phase-conjugate photon echoes is constructed to measure a sudden change in the index of refraction of a transparent medium. This novelty filter is set up as a Michelson interferometer and employs a europium-doped crystal as a phase-conjugate mirror. The filter is sensitive to the sudden change in index of refraction when the phase-conjugate echo experiences a different path length from the first laser excitation pulse in a photon-echo experiment. Using a Pockels cell as a pure phase modulator, we demonstrate that the filter can resolve a sudden phase change occurring on a nanosecond time scale with an accuracy and resolution close to 5°.

CHROMOPHORE-SOLVENT DYNAMICS

▪ Abstract Experimental and theoretical studies of polar solvation dynamics and spectral line broadening are described. Photon echo and fluorescence Stokes shift experiments are discussed, and the relationship between the information content of the two techniques clarified. The interaction of the chromophore with its solvent bath is described by a spectral density, and the connection of this spectral density with the liquid's instantaneous normal modes discussed. The ubiquity of the ultrafast phase of solvation dynamics is demonstrated, and a discussion of its physical origin given. The slower phases of solvation vary strongly from solvent to solvent. Molecular theories of liquid dynamics are able to rationalize such variations over at least a 2000-fold range of time scale. The review concludes with a brief discussion of the relevance of ultrafast solvation to chemical dynamics.

Femtosecond accumulated photon echoes excited by an incandescent lamp

Femtosecond accumulated photon echoes excited by an incandescent lamp have been observed. To our knowledge, this is the first observation of photon echoes excited by incoherent black-body radiation where no stimulated emission takes place. This indicates that any kind of light source can be used to excite photon echoes, a kind of nonlinear coherent transient phenomena, if the intensity is large enough or the sample has a long enough accumulation time of population grating. The black-body radiation may facilitate the extension of the possible spectral range of the photon echo experiment.

Mode suppression in the non-Markovian limit by time-gated stimulated photon echo

It is demonstrated that enhanced mode suppression in stimulated photon echo experiments can be obtained by diagonal time gating of the echo. This technique is especially important when the optical dynamics of the system is non-Markovian. A two-mode Brownian oscillator model is used to analyze the effect of time gating on the stimulated photon echo. The method is demonstrated on a dye solution of DTTCI in ethylene glycol at room temperature. Experimentally, time gating of the echo is accomplished by means of femtosecond phase-locked heterodyne detected stimulated photon echo. The vibrational dynamics in this system are explored by conventional stimulated photon echo experiments. Especially stimulated photon echo-maximum shift measurements are found to be particularly useful.

Two-dimensional nonlinear optics using Fourier-transform spectral interferometry

The second-order nonlinear-optical response of a material is measured in two dimensions of frequency. This new spectroscopy technique, based on the use of Fourier-transform spectral interferometry, is a transposition to optics of two-dimensional nuclear magnetic resonance. Although we demonstrate the technique by measuring the second-order phase-matching map of a nonresonant nonlinear crystal, this method should find useful applications in the measurement of second-order nonlinear susceptibility and in photon-echo experiments.

Dephasing-rephasing balancing in photon echoes by excitation induced frequency shifts.

The excitation dephasing in solids resulting from the interaction with neighboring species' excitations is investigated. The frequency shifts due to these interactions are identified by the observation of partial dephasing-rephasing balancing in bichromatic photon-echo experiments applied to rare-earth ion doped crystals. The experimental observations are in good agreement with the predictions obtained from a model which accounts for the disorder in the crystal and for the stochastic nature of the excitations.

System−Bath Correlation Function Probed by Conventional and Time-Gated Stimulated Photon Echo

We show how in the framework of the multimode Brownian oscillator model the system−bath correlation function can be derived from conventional and time-gated stimulated photon echo experiments and consideration of the linear optical spectra. Experiments are performed on the infrared dye DTTCI in room temperature solutions of ethylene glycol, methanol, and acetonitrile. The obtained correlation function is the sum of several Brownian oscillators, of which four are attributed to intrachromophore vibrational dynamics and the other three to solute−solvent dynamics. The ultrafast part of the correlation function on the time scale of the excitation pulses is interpreted as a free induction decay-like effect due to impulsive excitation of spectrally broad underlying vibrational structure in the dye's electronic transition. The slower parts are assigned to multiple time scale solute−solvent dynamics. The effect of vibrational coherences on the echo measurements is also analyzed; this analysis permits the dissection of the correlation function into a part due to intrachromophore dynamics and a part due to solvation dynamics. The spectral densities associated with these latter oscillators are located in the far infrared, in the same spectral region as probed by the optical Kerr effect. The measurements, however, provide no definite answer to the question of whether these spectral densities are the same.

Infrared Photon Echo Experiments: Exploring Vibrational Dynamics in Liquids and Glasses

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfrared Photon Echo Experiments: Exploring Vibrational Dynamics in Liquids and GlassesA. Tokmakoff and M. D. FayerCite this: Acc. Chem. Res. 1995, 28, 11, 437–445Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://doi.org/10.1021/ar00059a001RIGHTS & PERMISSIONSArticle Views382Altmetric-Citations81LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Infrared vibrational photon echo experiments in liquids and glasses

Infrared vibrational photon echo experiments in liquids and glasses