Time resolved observation of resonant and non-resonant contributions to the nonlinear susceptibility χ(3)

Zinth, Wolfgang; Laubereau, A.; Kaiser, W.

doi:10.1016/0030-4018(78)90246-8

Cited by 73 publications

(23 citation statements)

References 16 publications

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“…The second part on the r.h.s. of equation (2) is related to the nonresonant nonlinear susceptibility χ$ resulting from electronic contribu tions [15]. The nonresonant part of the signal gives an instantaneous response, i.e.…”

Section: Theorymentioning

confidence: 99%

Terahertz beats of vibrational modes studied by femtosecond coherent Raman spectroscopy

Leonhardt

Holzapfel

Zinth

et al. 1987

Rev. Phys. Appl. (Paris)

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Co-Editcurs-Texte en trois exemplaires, dactylographies en double interligne au recto seulement, avec marges de 4 cm au moins.-Resume dans la langue originale, en un seul paragraphe.-Traductions du titre et du resume en anglais et en frangais.-Titre abrege de 50 signes au plus, pour tetes de pages.-Legendes des figures et references numerotees sur pages separees.-Pour les articles en frangais, les legendes doivent etre ä la fois en frangais et en anglais.-Figures originales sur calque, numerotees au crayon ; joindre une copie ä chaque exemplaire du texte.-Numeros de code dans Physics Abstracts.

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Section: Theorymentioning

confidence: 99%

Terahertz beats of vibrational modes studied by femtosecond coherent Raman spectroscopy

Leonhardt

Holzapfel

Zinth

et al. 1987

Rev. Phys. Appl. (Paris)

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“…(v) The scattering process may also be performed on the anti-Stokes part of the spectrum. The disturbing interference found in stationary CARS spectroscopy does not occur for the delayed probing used with SEPI spectroscopy [4,9,10]. (vi) A simul-taneous measurement of the coherent Stokes and antiStokes SEPI spectra allows us to eliminate the effect of a chirped probing pulse.…”

Section: Additional Observations and Commentsmentioning

confidence: 99%

A new Raman technique of superior spectral resolution

Nuss¹,

Kaiser²

1982

Chemical Physics Letters

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Raman-active vibrational modes are coherently excited by the transient stimulated Raman process. A subsequent delayed probe of relativelylong duration interacts with the freely relaxing vibrations. Raman spectra are generated with higher resolution and more accurate peak positions than in conventional Raman spectroscopy. In liquid cyclohexane four new Raman lines were readily detected ha the frequency range 2870-2920 cm -t .

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“…We start with a single chirp-free infrared pulse from a passively mode-locked Nd:glass laser system [10]. The pulse is frequency doubled in a KDP crystal to PL = 18990 cm -1 .…”

Section: (3)mentioning

confidence: 99%

“…Self-focussing within the cell of 2 cm length is not observed and is not expected from numerical estimates. Care was taken to image only the central part of the transmitted laser beam [10] onto the slit of a 2 m grating spectrograph. In this way, the self-phase modulation of the intense part of the beam is clearly observed.…”

Section: (3)mentioning

confidence: 99%

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Frequency shifts in stimulated Raman scattering

Kaiser

1980

Optics Communications

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The nonresonant contributions to the nonlinear susceptibility x (3) produce a frequency chirp during stimulated Raman scattering. In the case of transient stimulated Raman scattering, the spectrum of the generated Stokes pulse is found at higher frequencies than expected from spontaneous Raman data. The frequency difference can be calculated from the theory of stimulated Raman scattering.It has been shown in numerous papers that an intense electromagnetic wave of frequency COL, travelling through a Raman active medium, is able to generate a strong Stokes shifted collinear wave at frequency coS. In most experimental investigations the Stokes shift coo = col --coS of the stimulated Raman process was found to be equal to the Stokes shift known from spontaneous Raman measurements [ 1 ]. In contradiction, there exists a number of papers where deviations in the Stokes shifts between stimulated and spontaneous Raman scattering were reported [2].In this note we present a theoretical and experimental study of the stimulated Raman process taking into account the self-phase modulation of the laser and Stokes wave. It will be shown that under quasistationary conditions the stimulated Stokes emission has the same Stokes shift as spontaneous Raman scattering. For the transient stimulated Raman process the situation is different. Theory predicts and experiments confirm a smaller Stokes shift, i.e. a higher Stokes frequency. For clarity, we consider here a specific case, Raman scattering of a molecular vibration in liquids. The theoretical discussion is quite general being applicable to other Raman type process as well.The nonlinear response of the molecules is represented by the nonlinear polarisation pNL, which may be separated into two parts: A resonant contribution PR NL due to the molecular transition of interest with a Raman susceptibility ~a/~q and a nonresonant part NL PNR due to the electronic states of the molecules [3].N is the number density of the molecules and denotes the expectation value of the normal mode operator q for the transition. For simplicity we make two assumptions: (i) A highly polarized Raman line is investigated, i.e. Oa/aq is a scalar. coO and m represent the transition frequency and the reduced mass, respectively, T 2 the dephasing time and n' is the occupation probability of the first excited vibrational level. For the system considered here we have a small population, i.e. n' < 1.For the light fields and the coherent material excitation, we make the ansatz of plane waves propagating in the x-direction: E = ~ {~ Ejexp(-ico/t + ikix + i~b/) + cc 1and ~q) = -~i{Q exp(-icoqt + ikqx + i~bq) + cc}.

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Time resolved observation of resonant and non-resonant contributions to the nonlinear susceptibility χ(3)

Cited by 73 publications

References 16 publications

Terahertz beats of vibrational modes studied by femtosecond coherent Raman spectroscopy

Terahertz beats of vibrational modes studied by femtosecond coherent Raman spectroscopy

A new Raman technique of superior spectral resolution

Frequency shifts in stimulated Raman scattering

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