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Artykuły w czasopismach na temat "TIME RESOLVED PUMP PROBE ULTRAFAST STIMULATED RAMAN"
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OCKMAN, NATHAN, WUBAO WANG i R. R. ALFANO. "APPLICATIONS OF ULTRAFAST LASER SPECTROSCOPY TO THE STUDY OF SEMICONDUCTOR PHYSICS". International Journal of Modern Physics B 05, nr 20 (grudzień 1991): 3165–234. http://dx.doi.org/10.1142/s0217979291001255.
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This article reviews the application of some of the principal methods of picosecond and femtosecond laser spectroscopy to the investigation of the dynamics of carriers, phonons and surface structure in semiconductors. The measurement of the temporal evolution of photoinduced luminescence, absorption, reflection and scattering in semiconductors makes it possible to obtain the lifetimes of photogenerated electrons, holes, excitons and phonons in both the bulk and quantum wells and superlattice structures. The information produced by these studies is necessary for the basic understanding of the underlying physics of semiconductors. In addition, the parameters obtained from these studies are needed for evaluating ultrafast transport, switching, photoconductive response and imaging in semiconductor materials, which will determine their limitations for use in high-speed and high-frequency devices and computers. For measuring time resolved luminescence, the principal techniques used, namely, the streak camera, the optical Kerr gate and the up-conversion gate are thoroughly discussed. Several pump and probe methods are described for the determination of time resolved absorption, reflection and Raman scattering. For absorption measurements where the probe wavelength differs from the pump, the former is generated in nonlinear media by means of stimulated Raman scattering and the supercontinuum for the UV and visible regions and by parametric and difference frequency generation for the near- and mid-IR. Nonlinear optics techniques considered are degenerate and nondegenerate four-wave mixing and transient grattings among which photon echoes yield the momentum relaxation of hot electrons. Coherent anti-Stokes Raman scattering (CARS) and phase conjugate Raman scattering (PC) are described to determine phonon dephasing times and the nonlinear susceptibility, χ3.
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Kuramochi, Hikaru, Satoshi Takeuchi, Hironari Kamikubo, Mikio Kataoka i Tahei Tahara. "Fifth-order time-domain Raman spectroscopy of photoactive yellow protein for visualizing vibrational coupling in its excited state". Science Advances 5, nr 6 (czerwiec 2019): eaau4490. http://dx.doi.org/10.1126/sciadv.aau4490.
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We report fifth-order time-domain Raman spectroscopy of photoactive yellow protein (PYP), with the aim to visualize vibrational coupling in its excited state. After the ultrashort actinic pump pulse prepared the vibrational coherence and population in the excited state, the evolving vibrational structure was tracked by time-resolved impulsive stimulated Raman spectroscopy using sub–7-fs pulses. The obtained fifth-order time-domain Raman data were translated to a two-dimensional (2D) frequency-frequency correlation map, which visualizes the correlation between low- and high-frequency vibrational modes of the excited state. The 2D map of PYP reveals a cross peak, indicating the coupling between the phenolic C─O stretch mode of the chromophore and the low-frequency modes (~160 cm−1), assignable to the intermolecular motions involving the surrounding hydrogen-bonded amino acids. The unveiled coupling suggests the importance of the low-frequency vibrational motion in the primary photoreaction of PYP, highlighting the unique capability of this spectroscopic approach for studying ultrafast reaction dynamics.
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Hutchison, Christopher D. M., i Jasper J. van Thor. "Optical control, selection and analysis of population dynamics in ultrafast protein X-ray crystallography". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, nr 2145 (kwiecień 2019): 20170474. http://dx.doi.org/10.1098/rsta.2017.0474.
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Ultrafast pump-probe X-ray crystallography has now been established at X-ray free electron lasers that operate at hard X-ray energies. We discuss the performance and development of current applications in terms of the available data quality and sensitivity to detect and analyse structural dynamics. A discussion of technical capabilities expected at future high repetition rate applications as well as future non-collinear multi-pulse schemes focuses on the possibility to advance the technique to the practical application of the X-ray crystallographic equivalent of an impulse time-domain Raman measurement of vibrational coherence. Furthermore, we present calculations of the magnitude of population differences and distributions prepared with ultrafast optical pumping of single crystals in the typical serial femtosecond crystallography geometry, which are developed for the general uniaxial and biaxial cases. The results present opportunities for polarization resolved anisotropic X-ray diffraction analysis of photochemical populations for the ultrafast time domain. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.
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Namboodiri, Mahesh, Tahirzeb Khan, Khadga Karki, Mehdi Mohammad Kazemi, Sidhant Bom, Günter Flachenecker, Vinu Namboodiri i Arnulf Materny. "Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging". Nanophotonics 3, nr 1-2 (1.04.2014): 61–73. http://dx.doi.org/10.1515/nanoph-2013-0044.
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AbstractThe combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.
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Bailey-Darland, Sullivan, Taylor D. Krueger i Chong Fang. "Ultrafast Spectroscopies of Nitrophenols and Nitrophenolates in Solution: From Electronic Dynamics and Vibrational Structures to Photochemical and Environmental Implications". Molecules 28, nr 2 (6.01.2023): 601. http://dx.doi.org/10.3390/molecules28020601.
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Nitrophenols are a group of small organic molecules with significant environmental implications from the atmosphere to waterways. In this work, we investigate a series of nitrophenols and nitrophenolates, with the contrasting ortho-, meta-, and para-substituted nitro group to the phenolic hydroxy or phenolate oxygen site (2/3/4NP or NP−), implementing a suite of steady-state and time-resolved spectroscopic techniques that include UV/Visible spectroscopy, femtosecond transient absorption (fs-TA) spectroscopy with probe-dependent and global analysis, and femtosecond stimulated Raman spectroscopy (FSRS), aided by quantum calculations. The excitation-dependent (400 and 267 nm) electronic dynamics in water and methanol, for six protonated or deprotonated nitrophenol molecules (three regioisomers in each set), enable a systematic investigation of the excited-state dynamics of these functional “nanomachines” that can undergo nitro-group twisting (as a rotor), excited-state intramolecular or intermolecular proton transfer (donor–acceptor, ESIPT, or ESPT), solvation, and cooling (chromophore) events on molecular timescales. In particular, the meta-substituted compound 3NP or 3NP− exhibits the strongest charge-transfer character with FSRS signatures (e.g., C–N peak frequency), and thus, does not favor nitroaromatic twist in the excited state, while the ortho-substituted compound 2NP can undergo ESIPT in water and likely generate nitrous acid (HONO) after 267 nm excitation. The delineated mechanistic insights into the nitro-substituent-location-, protonation-, solvent-, and excitation-wavelength-dependent effects on nitrophenols, in conjunction with the ultraviolet-light-induced degradation of 2NP in water, substantiates an appealing discovery loop to characterize and engineer functional molecules for environmental applications.
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Zhou, M., A. Otomo, S. Yokoyama i S. Mashiko. "Time-Resolved Spectral Measurement of Dendrimer Molecular Films with Rhodamine B Core". MRS Proceedings 708 (2001). http://dx.doi.org/10.1557/proc-708-bb3.16.
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ABSTRACTWe investigated molecular thin films fabricated using novel organic materials, such as dendrimers with a rhodamine B (Rh-B) core, by a pump-probe measurement for ultrafast time-resolved spectroscopy with a time resolution of approximately 160 fs. The photon energy transfer caused by the interaction of the dendrimer molecules was measured in terms of absorbance. The wavelength of the pump light was 550 nm and a white continuum light spanning from 450 nm to 750 nm was used as a probe light. A spin-coated molecular film made of dendrimer molecules with Rh-B core has a relatively high molecular density. We measured a strong stimulated emission at a wavelength of 612 nm, whose fast decay was assumed to be caused by intermolecular interactions between the dendrimer molecules with Rh-B core. The lifetime of the molecules in the excited state was measured to be as short as 10 ps. Several types of molecular films with different molecular densities were compared, and cases with different pump energies were also discussed.
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Redeckas, Kipras, Vladislava Voiciuk i Mikas Vengris. "A tunable femtosecond stimulated Raman scattering system based on spectrally narrowed second harmonic generation". Lithuanian Journal of Physics 56, nr 1 (26.04.2016). http://dx.doi.org/10.3952/physics.v56i1.3273.
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In this work we present a femtosecond stimulated Raman scattering system. The setup is based on a commercial femtosecond laser system supplemented by a pair of travelling-wave optical parametric amplifiers. One of the parametric amplifiers is used to generate the femtosecond actinic pump pulses, whereas the output of the other (high-power) parametric amplifier undergoes a combination of spectrally narrowed second harmonic generation in a long non-linear crystal and subsequent spectral filtering for the generation of narrowband Raman pump pulses. Chirped white light supercontinuum is used as the Raman probe. The setup offers tunability of the Raman pump pulses in the 400–800 nm range, and spectral and temporal resolutions of ca. 6 cm–1 and ca. 70 fs, respectively. We present the basic technical and optical aspects of the system along with data acquisition and signal retrieval techniques. We characterize the system by exploring the time-resolved vibrational dynamics of the S2(11Bu+) and S1(21Ag–) excited states of β-carotene.
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Bartram, F. Michael, Yu-Chen Leng, Yongchao Wang, Liangyang Liu, Xue Chen, Huining Peng, Hao Li i in. "Ultrafast coherent interlayer phonon dynamics in atomically thin layers of MnBi2Te4". npj Quantum Materials 7, nr 1 (29.08.2022). http://dx.doi.org/10.1038/s41535-022-00495-x.
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AbstractThe atomically thin MnBi2Te4 crystal is a novel magnetic topological insulator, exhibiting exotic quantum physics. Here we report a systematic investigation of ultrafast carrier dynamics and coherent interlayer phonons in few-layer MnBi2Te4 as a function of layer number using time-resolved pump-probe reflectivity spectroscopy. Pronounced coherent phonon oscillations from the interlayer breathing mode are directly observed in the time domain. We find that the coherent oscillation frequency, the photocarrier and coherent phonon decay rates all depend sensitively on the sample thickness. The time-resolved measurements are complemented by ultralow-frequency Raman spectroscopy measurements, which both confirm the interlayer breathing mode and additionally enable observation of the interlayer shear mode. The layer dependence of these modes allows us to extract both the out-of-plane and in-plane interlayer force constants. Our studies not only reveal the interlayer van der Waals coupling strengths, but also shed light on the ultrafast optical properties of this novel two-dimensional material.
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Mincigrucci, R., J. R. Rouxel, B. Rossi, E. Principi, C. Bottari, S. Catalini, J. S. Pelli-Cresi i in. "Element- and enantiomer-selective visualization of molecular motion in real-time". Nature Communications 14, nr 1 (24.01.2023). http://dx.doi.org/10.1038/s41467-023-36047-5.
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AbstractUltrafast optical-domain spectroscopies allow to monitor in real time the motion of nuclei in molecules. Achieving element-selectivity had to await the advent of time resolved X-ray spectroscopy, which is now commonly carried at X-ray free electron lasers. However, detecting light element that are commonly encountered in organic molecules, remained elusive due to the need to work under vacuum. Here, we present an impulsive stimulated Raman scattering (ISRS) pump/carbon K-edge absorption probe investigation, which allowed observation of the low-frequency vibrational modes involving specific selected carbon atoms in the Ibuprofen RS dimer. Remarkably, by controlling the probe light polarization we can preferentially access the enantiomer of the dimer to which the carbon atoms belong.
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Hortensius, J. R., D. Afanasiev, A. Sasani, E. Bousquet i A. D. Caviglia. "Ultrafast strain engineering and coherent structural dynamics from resonantly driven optical phonons in LaAlO3". npj Quantum Materials 5, nr 1 (grudzień 2020). http://dx.doi.org/10.1038/s41535-020-00297-z.
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AbstractStrain engineering has been extended recently to the picosecond timescales, driving ultrafast metal–insulator phase transitions and the propagation of ultrasonic demagnetization fronts. However, the nonlinear lattice dynamics underpinning interfacial optoelectronic phase switching have not yet been addressed. Here we perform time-resolved all-optical pump-probe experiments to study ultrafast lattice dynamics initiated by impulsive light excitation tuned in resonance with a polar lattice vibration in LaAlO3 single crystals, one of the most widely utilized substrates for oxide electronics. We show that ionic Raman scattering drives coherent rotations of the oxygen octahedra around a high-symmetry crystal axis. By means of DFT calculations we identify the underlying nonlinear phonon–phonon coupling channel. Resonant lattice excitation is also shown to generate longitudinal and transverse acoustic wave packets, enabled by anisotropic optically induced strain. Importantly, shear strain wave packets are found to be generated with high efficiency at the phonon resonance, opening exciting perspectives for ultrafast material control.
Rozprawy doktorskie na temat "TIME RESOLVED PUMP PROBE ULTRAFAST STIMULATED RAMAN"
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Challa, Jagannadha Reddy. "Electronic and Vibrational Dynamics of Heme Model Compounds-An Ultrafast Spectroscopic Study". Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1181323422.
Pełny tekst źródłaCzęści książek na temat "TIME RESOLVED PUMP PROBE ULTRAFAST STIMULATED RAMAN"
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Cina, Jeffrey A. "How fissors works: Femtosecond stimulated Raman spectroscopy as a probe of conformational change". W Getting Started on Time-Resolved Molecular Spectroscopy, 34–52. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780199590315.003.0004.
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The theory and interpretation of femtosecond stimulated Raman spectroscopy (FSRS or fissors) are explored. This form of vibrational spectroscopy uses an ultrashort, electronically resonant launch pulse and concurrently arriving narrow-band Raman pump and broadband Raman probe pulses. FSRS provides information on relatively slow conformational motion though its anharmonic coupling to higher-frequency vibrations.
Streszczenia konferencji na temat "TIME RESOLVED PUMP PROBE ULTRAFAST STIMULATED RAMAN"
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Cho, G. C., W. Kiitt, M. Strähnen, A. Esser, U. Lemmer i H. Kurz. "Direct Time Resolved Observation of Coherent Phonon Oscillations in Ill-V-compounds". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.thd7.
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Femtosecond time resolved coherent phonon oscillations are observed for the first time through impulsive stimulated Raman scattering (ISRS)/1/ in semiconductor Ill-V-compounds. Individual cycles of the phonon oscillations as well as the vibrational dephasing are demonstrated via a modulation of the time resolved reflectivity signatures through the electro-optic effect. The observed linear behaviour of oscillation amplitude on pump intensity confirms the excitation of coherent longitudinal polar optic phonons with a single femtosecond pulse via ISRS in GaAs, InP and AIGaAs. The macroscopic electric field associated with the lattice vibrations is measured via the electro-optic effect. This is confirmed through the distinct variation of reflectivity signal modulation versus relative orientation of probe beam polarization and crystal orientation in our pump/probe experiments.
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Dorsinville, R., P. Delfyett, A. Walser i R. R. Alfano. "Time resolved Raman induced phase conjugation in polymers and semiconductors". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/up.1986.thc6.
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Time resolved Raman induced phase conjugation (TRIPC) and degenerate four wave mixing were used to investigate the magnitude and time response of the third order nonlinearity as well as vibrational and photon relaxation times in different liquids and solids. A phase conjugation geometry was used in these experiments with two counter propagating picosecond pump beams and a picosecond probe beam interacting in a nonlinear medium and generating a phase conjugate signal beam. For the vibrational and phonon relaxation time measurements one of the picosecond counter propagating beams was a broadband super continuum extending throughout the visible spectrum. By delaying one of the interacting pump beams relative to the other pump and probe beams we were able to determine, with picosecond resolution, the intensities of both the degenerate and Stokes shifted phase conjugate signals as a function of time. We have applied these techniques to determine the magnitude of the third order nonlinearity of several polymer and semiconductor samples and to measure the temporal behavior of the nonlinear interactions with picosecond resolution. TRIPC has been used for obtaining fundamental information about resonant vibrational interactions. In particular TRIPC spectra in CS2, nitrobenzene, and calcite, spanning 3000 cm−1 have been obtained. By delaying one of the pump beams and monitoring the intensity of a desired Stokes frequency component, information about the vibrational dephasing time was obtained. Performing the time resolved experiment in CS2 and calcite, a vibrational dephasing time of 24 ps for the 656 cm−1 vibration in CS2, and 8 ps for the 1086 cm−1 vibration in calcite were measured. The lifetimes are in good agreement with the work of Fisher and Lauberau (Chem Phys. Lett. 35, 6(1975)) (22 ps for CS2) and Alfano and Shapiro (Phys. Rev. Lett. 26, 1247 (1971)) (8.5 ps for calcite ) using conventional picosecond time resolved excite and probe Raman techniques. These experimental results and measurements in several other samples will be discussed.
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Seel, Matthias, i Wolfgang Domcke. "Femtosecond time-resolved ionization spectroscopy of polyatomic molecules". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.tuc21.
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It is generally appreciated that femtosecond pump-probe techniques have the potential to provide novel and important information on elementary photophysical and photochemical processes. It has been demonstrated by several applications that time-resolved two-pulse ionization, that is, optical excitation and subsequent ionization of a molecular system with two short laser pulses, is a promising tool to observe excited state dynamics in real time.1 In comparison to alternative real-time probing techniques such as stimulated emission or excited-state absorption with fluorescence detection, two-pulse ionization spectroscopy possesses the advantage of extreme sensitivity of signal detection. The possibility of recording, for each pulse configuration, a complete photoelectron spectrum suggests that time-resolved ionization spectroscopy may be able to yield unprecedentedly detailed information on ultrafast intramolecular processes.
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Johnson, Alan E., i Anne B. Myers. "Comparison of Spontaneous and Impulsive Stimulated Resonance Raman Excitation Profiles". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.sab.5.
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Spontaneous resonance Raman (RR)1 and resonant impulsive stimulated Raman scattering (RISRS)2 both contain vibrationally specific information about the structure and dynamics of a resonant excited electronic state, even when that state has a very short (sub-vibrational period) lifetime. Steady-state RR cross sections have a time-domain interpretation in which the laser field transfers part of the initial ground-state wavefunction to the excited state surface, and the spectrum of the spontaneously emitted light provides information on the evolution of that excited-state amplitude on the upper surface. In RISRS, a femtosecond pump pulse drives the initial thermal equilibrium state into a coherent superposition of ground-state vibrational levels, and a delayed probe pulse monitors the resulting perturbation of the chromophore's absorption. This time-domain signal can be Fourier transformed to give a spectrum usually dominated by Franck-Condon active vibrational frequencies of the ground state. However, the Fourier transform of the RISRS signal (FT-RISRS) is by no means equivalent to a RR spectrum, and important qualitative errors of interpretation can result if this assumption is made.3
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Schröder, T., P. Heist, S. Govorkov, I. Shumay i W. Rudolph. "Investigation of Femtosecond Pulse Induced Phase Transitions in GaAs". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.tuc23.
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There has been a great deal of interest in the investigation of the primary steps of phase transitions at semiconductor surfaces excited by an ultrashort laser pulse. Raman experiments [1] revealed that energy from the electronic system is transferred to the phonon system (lattice) on a time scale of about 1-2ps. Direct observation of the sample surface after excitation showed the onset of melting to be within a few or less than 1ps [2]. Second harmonic generation in reflection turned out to be a powerful tool to detect symmetry changes of the sample surface [3-5]. The general observation is that the drop of the second harmonic efficiency occurs within the first one hundred fs after excitation. In contrast the reflectivity of the fundamental changes on a time scale of several hundred fs up to one ps depending on the excitation density. While the SHG probes only about a layer of lOnm the reflectivity of the fundamental is determined by a layer thickness of several hundred nm. Therefore one possible explanation for the different time constants rests on propagation effects of the melt front, another assumes an intermediate state reflecting a changed lattice symmetry which is reached before a considerable part of energy is transferred to the phonon system (cold melting) [3]. We supplemented pump-probe and time resolved SHG in reflection by transient grating measurements. The latter are extremly sensitive against propagation effects because they change the grating structure and thus the diffraction efficiency. Corresponding measurements are shown in Fig.l. It is intresting to note that observable first-order diffraction occured only at excitation densities above the melting threshold. From Fig.1 it is evident that the diffraction dynamics is similar to that of the fundamental reflection. A theoretical model explains this as a consequence of the fact that propagation effects can be neglected within the first few ps. An upper limit for the velocity of the melt front velocity can be estimated and is in the order of 500 m/s. Since the diffraction rise time of the UV-probe (310nm) is considerably longer than the decay of the second harmonic efficiency the existence of an intermediate state or phase prior the melting becomes even more likely.