Capturing One-Dimensional Precursors of a Photoinduced Transformation in a Material

Guérin, Laurent; Hebert, Johan; Cointe, Marylise Buron-Le; Adachi, Shin‐ichi; Koshihara, Shin‐ya; Cailleau, H.; Collet, Éric

doi:10.1103/physrevlett.105.246101

Cited by 46 publications

(50 citation statements)

References 32 publications

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“…The most direct observation of such nano-objects, with an internal structural coherence but incoherently distributed in the crystal, is realized through time-resolved diffuse scattering [50]. These phototransformed entities may cooperatively interact with the atoms/molecules in the surroundings.…”

Section: Nanodomains Vs Softeningmentioning

confidence: 99%

PIPT from the Beginning to Future

et al. 2012

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The birth of the field of photoinduced phase transitions was strongly influenced by the conceptual viewpoint expressed by Professor Y. Toyozawa on the condensation of relaxed excitons. Since this first period, twenty years ago, this young field has been expanding rapidly along a diversity of directions. Nowadays, it goes hand in hand with the challenges of today's science: emergence, nonlinearity, coherence, far away from equilibrium, for example. The control of the functionality of a material via photoexcited states poses many new fundamental questions. Some of them will be overviewed: (i) the nature of the control parameters and the nature of the relevant collective variables, especially the order parameters, which characterize the evolution of the system, (ii) the difference between photoinduced transformations under continuous light irradiation and those resulting from an ultrashort laser pulse, (iii) the physical mechanisms of ultrafast photoinduced phase transitions from the formation and proliferation of phototransformed entities to the softening of a collective mode. 78.47.D- Flash-backThis paper is dedicated in memoriam of Professor Yutaka Toyozawa, a founding father of the field of photoinduced phase transitions (PIPT). After the pioneering experimental work of Koshihara on the observation of the photoinduced neutral-to-ionic instability [1], the paper of Prof. Y. Toyozawa, "Condensation of relaxed excitons in static and dynamic phase transitions" [2], is the fingerprint of his inspiring contribution. He brought out some conceptual keys which strongly influenced our research and that of many of our colleagues. In the conclusion of this paper he emphasizes "the usefulness of the global view-point . . . considering the crossover of the excited and the ground electronic states and correlating static and dynamic phase transitions through the motion of (spontaneously or optically) condensed elementary excitations".A second step was the Taniguchi symposium in 1996 "Relaxations of excited states and photoinduced phase transitions" chaired by Prof. Nasu [3]. The aim of this symposium was to discuss the new problem of unconventionally photoactive materials. In these materials the relaxation of optically excited states result in collective motions or drastic structural changes, involving a large number of atoms and electrons. Actually, in a way this symposium was the precursor of the PIPT conferences. The extension of the physics of self-trapped excitons, which Toyozawa has largely contributed to [4], to systems with electron-spin-lattice cooperative interactions was discussed from the viewpoint of both material science and solid state spectroscopy. * corresponding author; e-mail:herve.cailleau@univ-rennes1.frThroughout this first period different theoretical papers were published, developing this approach to establish some backgrounds in the understanding of photoinduced phase transitions [3,5,6]. At the same period, different approaches of photoinduced phase transitions were introduced [7], in particular to t...

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Section: Nanodomains Vs Softeningmentioning

confidence: 99%

PIPT from the Beginning to Future

et al. 2012

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“…Time-resolved terahertz spectroscopy is a technique of probing electronic structures in a very low energy range [23]. Time-resolved diffraction measurements such as X-ray scattering and electron diffraction are techniques used to directly observe lattice/molecular structural changes and they have been the subject of several recent studies [6,24,25]. These advancements in new techniques reveal new aspects of the dynamics of PIPT and have attracted many researchers to this field.…”

Section: K) Is Extremely Large Compared With Its Thermal Energy (~K)mentioning

confidence: 99%

Photoinduced Phase Transition in Strongly Electron-Lattice and Electron–Electron Correlated Molecular Crystals

2012

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Strongly electron-lattice-and electron-electron-correlated molecular crystals, such as charge transfer (CT) complexes, are often sensitive to external stimuli, e.g., photoexcitation, due to the cooperative or competitive correlation of various interactions present in the crystals. These crystals are thus productive targets for studying photoinduced phase transitions (PIPTs). Recent advancements in research on the PIPT of CT complexes, especially Et 2 Me 2 Sb[Pd(dmit) 2 ] 2 and (EDO-TTF) 2 PF 6 , are reviewed in this report. The former exhibits a photoinduced insulator-to-insulator phase transition with clearly assigned spectral change. We demonstrate how to find the dynamics of PIPT using this system. The latter exhibits a photoinduced hidden state as an initial PIPT process. Wide energy ranged time-resolved spectroscopy can probe many kinds of photo-absorption processes, i.e., intra-molecular and inter-molecular electron excitations and intramolecular and electron-molecular vibrations. The photoinduced spectral changes in these photo-absorption processes reveal various aspects of the dynamics of PIPT, including electronic structural changes, lattice structural changes, and molecular deformations. The complexities of the dynamics of the latter system were revealed by our measurements. OPEN ACCESSCrystals 2012, 2 1068

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“…This phase transition originates from competition between an ionization-energy difference and a long-range Coulomb energy gain [14][15][16]. To date, both PIPTs from neutral to ionic (N-to-I) and from ionic to neutral (I-to-N) were observed, and various processes and phenomena were revealed while the PIPTs take place [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…Tetrathiafulvalene-p-chloranil (TTF-CA) is one of the most intensively studied materials in terms of photoinduced phase transition (PIPT) [1][2][3][4][5][6][7][8][9][10][11][12][13]. TTF-CA is a mixed stack charge transfer complex consisting of donor (D = TTF) and acceptor (A = CA) molecules.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Ionic to Neutral Phase Transition in TTF-CA Studied by Time-Resolved Infrared Vibrational Spectroscopy

et al. 2012

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We studied the photoinduced ionic to neutral phase transition in tetrathiafulvalene-p-chloranil (TTF-CA) using time-resolved infrared vibrational spectroscopy. By monitoring the charge sensitive b 1u ν 10 band of CA after photoexcitation by a 1.55 eV pulse, we found that the photoinduced N-phase has the same charge of the N-phase in thermal equilibrium and there is no charge variation during the photoinduced phase transition. We also found that the photoinduced N-phase grows through at least two steps over 300 ps.

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Capturing One-Dimensional Precursors of a Photoinduced Transformation in a Material

Cited by 46 publications

References 32 publications

PIPT from the Beginning to Future

PIPT from the Beginning to Future

Photoinduced Phase Transition in Strongly Electron-Lattice and Electron–Electron Correlated Molecular Crystals

Photoinduced Ionic to Neutral Phase Transition in TTF-CA Studied by Time-Resolved Infrared Vibrational Spectroscopy

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