Terahertz beats of vibrational modes studied by femtosecond coherent Raman spectroscopy

Leonhardt, R.; Holzapfel, W. B.; Zinth, Wolfgang; Kaiser, W.

doi:10.1051/rphysap:0198700220120173500

Cited by 53 publications

(24 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[5][6][7][8][9][10][11][12] This probe technique has been developed as a variant of fs time-resolved CARS (tr-CARS), [13][14][15][16][17][18][19][20][21][22][23][24][25] the history of which has been described thoroughly in recent reviews. 26,27 Hybrid fs/ps CARS utilizes the same four-wave-mixing excitation scheme as does fs tr-CARS; however, the use of a time-delayed, narrowband, ps-duration probe pulse-rather than a broadband, fs-duration probe pulse-allows direct frequency-domain detection of Raman-active molecular states.…”

Section: Introductionmentioning

confidence: 99%

Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

Stauffer¹,

Miller²,

Slipchenko³

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

The hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of timedependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated timeand frequency-domain spectral signatures of gas-phase species produced by hybrid fs/ps CARS are explored with a focus on gas-phase N2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs/ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowband final pulse. Additionally, we discuss the virtues of a frequencydomain Lorentzian probe-pulse lineshape and its potential for improving the hybrid fs/ps CARS technique as a diagnostic in high-pressure gas-phase thermometry applications. The hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated timeand frequency-domain spectral signatures of gas-phase species produced by hybrid fs/ps CARS are explored with a focus on gas-phase N 2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs/ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowba...

show abstract

Section: Introductionmentioning

confidence: 99%

Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

Stauffer¹,

Miller²,

Slipchenko³

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…The basic features of the experimental system are as follows [16]: Picosecond pulses from a mode-locked argon-ion laser synchronously pump two dye lasers. The Stokes pulses are generated in a standard synchronously mode-locked picosecond dye laser (dye DCM) with a three-plate birefringent filter providing a tunability at the Stokes frequency of our experiment between 15,600 and 14,500cm-1.…”

Section: Methodsmentioning

confidence: 99%

“…3. Here we plotted the normalized coherent signal as a function of the delay time for different settings of the spectrometer from OOA/2~e L" The main features of the signal curve are as follows: At small anti-Stokes frequencies, e.g., 16.760 em-1 and 16.830 cm-1, the nonresonant part of the signal dominates: At time zero a pronounced peak is found which follows the autocorrelation trace (broken curve). With increasing frequencies the resonant contribution to the signal (at later delay times) becomes more important and a dip shows up at a delay time of to~200fs (coa/2rcc= 16.900cm-1, 16.970 cm-1).…”

Section: Time Resolved Coherent Raman Scattering Of the 992 Cm-1 Modementioning

confidence: 99%

The influence of phase-modulation on femtosecond time-resolved coherent Raman spectroscopy

Holzapfel

Leonhardt

1988

Appl. Phys. B

Self Cite

View full text Add to dashboard Cite

Abstract. The influence of phase-modulation on femtosecond time-resolved coherent Raman scattering is investigated theoretically and experimentally. The coherent Raman signal taken as a function of the spectral position shows unexpected temporal oscillations close to time zero. A theoretical analysis of the coherent Raman scattering process indicates that the femtosecond fight pulses are amplitude and phase modulated. The pulses are asymmetric in time with more slowly decaying trailing wings. The phase of the pulse amplitude contains quadratic and higher-order contributions. PACS: 42.65, 42.80 Since the advent of the colliding-pulse mode-locking in 1981 light pulses shorter than 100fs have found extensive application in the study of ultrafast phenomena [1]. Various novel laser techniques have been developed to generate intense and reproducible femtosecond light pulses [24]. The different laser systems show interesting common features: (i) the shortest pulses are generated in the red wing of the gain and absorption spectrum of the amplifying and modelocking dyes. (ii) The dispersion in the resonator has to be compensated carefully. (iii) The spectra of the light pulses usually are asymmetric showing a steeper decay in the red part of the spectrum. The latter indicates that the light pulses are phase-modulated. Phase modulation or chirp have been discussed since the first publications on colliding-pulse mode-locked lasers [1,5]. Direct experimental determination of phase modulation offemtosecond light pulses was performed recently by numerical deconvolution or fitting of measured correlation traces [6][7][8][9]. The significance of the phase modulation on the results of ultrafast experiments was addressed by Fujimoto et al. [10], where the influence of phase-modulation on a timeresolved transmission experiment was demonstrated.In this paper we investigate the effect of phasemodulation on time-resolved coherent Raman scattering. The experimental data show unexpected modulations close to time zero, which can be explained by certain amplitude and phase properties of the femtosecond light pulses. Theory of Time-Resolved Coherent Raman ScatteringThe principle of time-resolved coherent Raman scattering has been treated in a number of publications [11,12]. At time zero two short light pulses at the laser and the Stokes frequency (center frequencies f2 L and f2s, respectively) enter the sample and excite a molecular vibration at the frequency f2q via transient stimulated Raman scattering. The light fields are written as plane waves, e.g., EL= 89 ) +C.C., where phase-modulation is contained in the complex function EL(t ) . In our experiments the laser pulses are much shorter than the Stokes pulses and the time dependence of the driving force FOZEL(t)E~(t ) is only determined by the laser field, F(t) = EL(t)E~. E~ is the effective Stokes amplitude averaged over the duration of the laser pulse. The coherent vibrational excitation is represented by the coherent amplitude ( q) = i/2Q(t) exp( -if2qt) + c.c.: t Q(t) = ~2 ~ dt...

show abstract

“…The large uncertainty of š120 fs has been estimated mainly by taking into account the strong oscillatory structure within the overall signal. Recalling that the contribution of every individual excited mode j is maximum at its wavenumber position Q j and has a spectral width that is equal to the one of the probe laser pulse [Eqn (7)], we can, as a rough approximation, infer that the vibrational relaxation of all excited modes occurs on a similar time-scale.…”

Section: Vibrational Dephasingmentioning

confidence: 99%

Two‐dimensional probing of ground‐state vibrational dynamics in porphyrin molecules by fs‐CARS

Heid

Schlücker

Schmitt

et al. 2001

J Raman Spectroscopy

View full text Add to dashboard Cite

We report on spectrally dispersed femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) for the investigation of the electronic ground-state vibrational dynamics of porphyrin molecules in solution. The two-dimensional experimental data obtained in our measurements provide a detailed mapping of the large number of molecular vibrations in these systems, excited by broadband ultrashort laser pulses, and make a thorough interpretation of the complex signal structure possible. In particular, an analysis of the data by applying Fourier transform methods to the time domain signal allows a clear identification of the excited porphyrin normal modes when compared with results on the mode structure from spectrally resolved (cw) spectroscopy. Altogether the method is capable of yielding detailed information on the dephasing behavior and on the relative spectral positions of the excited vibrations at the same time. Three porphyrin systems, dissolved in dichloromethane, were investigated: magnesium octaethylporphyrin, magnesium tetraphenylporphyrin and the free-base porphyrin octaethylporphyrin. The measurements were performed in the spectral region of the ring vibrations of the porphyrin macrocycle. We also provide a discussion of the expected signals on a theoretical basis by deriving the CARS third-order non-linear polarization for these experiments.

show abstract

Terahertz beats of vibrational modes studied by femtosecond coherent Raman spectroscopy

Cited by 53 publications

References 18 publications

Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

The influence of phase-modulation on femtosecond time-resolved coherent Raman spectroscopy

Two‐dimensional probing of ground‐state vibrational dynamics in porphyrin molecules by fs‐CARS

Contact Info

Product

Resources

About