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Cavalleri, A.; Chong, H.H.W.; Fourmaux, S.; Glover, T. E.; Heimann, P. A.; Kieffer, J. C.; Mun, Bongjin Simon; Padmore, H. A.; Schoenlein, R. W.

doi:10.1103/physrevb.69.153106

Cited by 82 publications

(52 citation statements)

References 27 publications

(16 reference statements)

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“…6). Optical studies of the M-R transition with femtosecond time resolution have indicated from reflectivity measurements that the transition occurs in Ϸ100 fs in thin samples (50 nm) (18). However, when the sample thickness was increased (200 nm film), a rise time of 2.9 ps was observed, remarkably in close agreement with our reported rise time of 3.1 ps.…”

Section: Resultssupporting

confidence: 82%

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Four-dimensional ultrafast electron microscopy of phase transitions

Grinolds

Lobastov

Weissenrieder

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

112

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Reported here is direct imaging (and diffraction) by using 4D ultrafast electron microscopy (UEM) with combined spatial and temporal resolutions. In the first phase of UEM, it was possible to obtain snapshot images by using timed, single-electron packets; each packet is free of space-charge effects. Here, we demonstrate the ability to obtain sequences of snapshots (''movies'') with atomic-scale spatial resolution and ultrashort temporal resolution. Specifically, it is shown that ultrafast metal-insulator phase transitions can be studied with these achieved spatial and temporal resolutions. The diffraction (atomic scale) and images (nanometer scale) we obtained manifest the structural phase transition with its characteristic hysteresis, and the time scale involved (100 fs) is now studied by directly monitoring coordinates of the atoms themselves.imaging ͉ diffraction ͉ electron crystallography ͉ vanadium dioxide E lectron microscopy has become a pivotal tool in numerous fields of study, from materials to biological imaging. In a previous publication (1), we introduced the concept of singleelectron imaging for the development of 4D ultrafast electron microscopy (UEM). The potential of UEM was demonstrated by obtaining images and diffraction patterns of materials and biological cells (1), and the scope of future applications has been highlighted in recent commentaries and reviews (refs. 2 and 3; see also ref. 4 and references therein). Because single-electron packets have no significant space-charge broadening, images and diffraction patterns are observed with atomic-scale spatial resolution and with the time resolution being fundamentally determined by the ultrashort duration of the optical pulse introduced to generate the photoelectrons in the microscope.The images and diffraction patterns reported (1) were ''snapshots'' at a particular point in time. However, as shown in Fig. 1, by delaying a second initiating optical pulse to arrive at the sample in the microscope with controlled time steps, it is possible to obtain a series of such snapshots with a well defined frame time. Unlike optical pump-probe experiments, this experimental task, for the microscope, is technically nontrivial for a number of reasons. To determine the zero time point, the clocking of the electron packet and optical pulse at the sample must be made with femtosecond time precision. Moreover, in contrast to these all-optical experiments, the cross-correlation between electron and photon pulses requires a new methodology. In addition, for 120-keV electrons, the group velocity of electron packets in the microscope is two-thirds the speed of light, and care has to be taken to account for this group velocity mismatch. Overcoming these hurdles in conjunction with attaining high quality, nanometer-scale samples in the microscope provides the capability of observing the dynamical changes of systems in the far-fromequilibrium state with the combined resolutions mentioned above.With the 4D UEM arrangement shown in Fig. 1, we demonstrate such studies of...

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Section: Resultssupporting

confidence: 82%

“…By increasing the fluence and time between pulses we should be able to map out the transition in different regions of the hysteresis and phases. We will also compare our UEM results with those obtained by using x-ray diffraction and optical studies (18,25) and with those obtained for different composition materials.…”

Section: Resultsmentioning

confidence: 99%

Four-dimensional ultrafast electron microscopy of phase transitions

Grinolds

Lobastov

Weissenrieder

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

112

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“…Understanding the dynamics driven by intense optical radiation is of fundamental importance to a diverse set of fields, ranging from structural phase transitions [1][2][3][4] to biophysics 5,6 . In solid state systems, for example, upon ultrafast optical excitation, the resultant impulsive surface heating can produce a transient longitudinal acoustic pulse.…”

mentioning

confidence: 99%

Reconstructing longitudinal strain pulses using time-resolved x-ray diffraction

et al. 2013

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Time-resolved x-ray diffraction is a very powerful tool for visualizing transient one-dimensional crystalline strains, ranging from crystal growth to shockwave production. In this work, we use picosecond x-ray diffraction to visualize transient strain formation from nanometer scaled laser excited gold films into crystalline substrates. We show that there is a direct correspondence between the measured time-resolved x-ray diffraction pattern and the transient acoustic wave, providing a straightforward method to make a reconstruction of the transient strain. In addition, we discuss real-world experimental constraints that place limits on the validity of the reconstructed transient acoustic wave.

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“…La résolution temporelle ultime obtenue avec une caméra à balayage de fente est de quelques centaines de femtoseconde en un seul tir laser et autour d'une picoseconde en mode accumulation [16,17]. Des études de spectroscopies d'absorption de rayonnement X résolus en temps ont également été réalisées avec une source synchrotron avec une résolution temporelle picoseconde, par exemple sur du silicium liquide [18] ou sur des transition de phase solide-solide [19].…”

Section: Introductionunclassified

“…La gamme d'énergie est 500-560 eV, proche du seuil L du vanadium et du seuil K de l'oxygène. Des expériences de référence ont été réalisées avec le rayonnement X produit par le synchrotron ALS (Advance Ligth Source, Berkeley Lab) sur une échelle de temps picoseconde [19], et sur une échelle de temps femtoseconde [20] en utilisant la technique de découpage laser (slicing) qui permet d'isoler un flash de 300 fs de rayonnement X synchrotron. Nous pensons qu'il est possible de réaliser une expérience similaire mais beaucoup plus compacte et simple en utilisant une source laser très intense et une caméra à balayage de fente comme détecteur.…”

Section: Introductionunclassified

Source X-UV pour la spectroscopie d'absorption en régime femtoseconde

et al. 2006

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Résumé. Les processus dynamiques se produisant lors de transitions de phase ultra-rapide peuvent être déduits à partir de mesures de diffraction ou d'absorption de rayonnement X. Les lasers femtosecondes ont récemment été utilisés pour étudier la dynamiques de la matière au moyen d'une pompe optique et d'une sonde X : du rayonnement X K alpha produit par interaction laser plasma. Nous présentons nos plus récents résultats concernant le développement d'un sytème de spectroscopie d'absorption du rayonnement X (XAS) basée sur une source laser-plasma large bande dans la gamme 1-5 nm permettant d'atteindre une résolution temporelle femtoseconde. Le système est conçu pour sonder les dynamiques électroniques ayant lieu durant la transion de phase semiconducteur-métal du dyoxide de vanadium (VO2) lorsque celle-ci est initiée par une impulsion laser femtoseconde. Dans la présente expérience, un spectre large bande proche du seuil L du vanadium (511 eV) et du seuil K de l'oxygène (525 eV) du VO2 a été généré et mesuré avec un haut rapport signal sur bruit (100), une grande résolution spectrale ( E/E = 4.2 × 10 −3 ), et une résolution temporelle de 1,2 ps.

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Picosecond soft x-ray absorption measurement of the photoinduced insulator-to-metal transition inVO2

Cited by 82 publications

References 27 publications

Four-dimensional ultrafast electron microscopy of phase transitions

Four-dimensional ultrafast electron microscopy of phase transitions

Reconstructing longitudinal strain pulses using time-resolved x-ray diffraction

Source X-UV pour la spectroscopie d'absorption en régime femtoseconde

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