Kinetics of light-induced first-order phase transformation in molecular solids:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Fe</mml:mi><mml:mo>(</mml:mo><mml:mi>btr</mml:mi><mml:msub><mml:mo>)</mml:mo><mml:mn>2</mml:mn></mml:msub><mml:mo>(</mml:mo><mml:mi>NCS</mml:mi><mml:msub><mml:mo>)</mml:mo><mml:mn>2</mml:mn></mml:msub><mml:mo>∙</mml:mo><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">O</mml:mi></mm

Pillet, Sébastien; Legrand, Vincent; Sarwat, Mohamed; Lecomte, Claude

doi:10.1103/physrevb.74.140101

Cited by 59 publications

(33 citation statements)

References 20 publications

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“…The dynamics of like-spin-domain nucleation and growth for heterogeneous cooperative transitions has indeed been determined using kinetic thermo-and photocrystallographic techniques. [64][65][66] In the following, we analyze successively the effect of a rapid quench cooling from room temperature to 10 K, the LS→HS photoexcitation process, and the subsequent HS→LS relaxation regime.…”

Section: Resultsmentioning

confidence: 99%

Multimetastability, phototrapping, and thermal trapping of a metastable commensurate superstructure in a FeIIspin-crossover compound

et al. 2012

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The photoinduced switching and subsequent relaxation regime at cryogenic temperatures of the two-step spin-crossover compound [Fe(bapbpy)(NCS) 2 ] has been investigated by time-dependent photocrystallography. Upon photoexcitation from the low-spin (LS) state, a direct population of the metastable high-spin (HS) state occurs, without involving any intermediate structural state. The relaxation from the metastable HS state in isothermal conditions at 40 K proceeds in two successive steps associated with two symmetry breaking processes. The first step corresponds to the cooperative transformation to an intermediate superstructure, characterized by a long-range-ordered [HS-LS-LS] motif coupled to a commensurate displacive modulation, and concomitant with a tripling of the c axis of the unit cell (C2/c space group). The stabilization of the intermediate state is driven by strong molecule-lattice coupling. In the second stage, the intermediate state undergoes a transformation twinning triggered by lattice strain towards the LS state. The two-step relaxation is reminiscent of the two-step thermal transition of [Fe(bapbpy)(NCS) 2 ] and evidences multimetastability in the light-induced or relaxation regime. The long-range-ordered [HS-LS-LS] superstructure has also been trapped by rapid quench cooling to very low temperature, and has been structurally characterized.

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Section: Resultsmentioning

confidence: 99%

Multimetastability, phototrapping, and thermal trapping of a metastable commensurate superstructure in a FeIIspin-crossover compound

et al. 2012

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“…Finally, it has been shown that the HS ↔ LS transition is related to a domain nucleation, growth and coarsening process in the solid state, with an unprecedented light-induced structural reorganization. [20,23] We report here a detailed structural analysis of [Fe(btr) 2 -(NCS) 2 ]·H 2 O in various spin states, HS-1, LS, HS-2q, HS2p, by using X-ray diffraction measurements performed at two temperatures, 15 K and 130 K (Figure 1). The main goal of this study is the characterization of the structural reorganization related to the light-induced and thermally induced spin transitions independent of thermal contraction/expansion effects.…”

Section: (Ncs) 2 ] (Pm = N-2ј-pyr-mentioning

confidence: 99%

Optical, Magnetic and Structural Properties of the Spin‐Crossover Complex [Fe(btr)₂(NCS)₂]·H₂O in the Light‐Induced and Thermally Quenched Metastable States

Legrand

Pillet²,

Carbonera

et al. 2007

Eur J Inorg Chem

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Keywords: Iron(II) / Photoswitching / Structural analysis / Photomagnetism / Spin crossover [Fe(btr) 2 (NCS) 2 ]·H 2 O [btr = 4,4Ј-bis(1,2,4-triazole)] is the archetype of highly cooperative and low-dimensional spincrossover complexes, which exhibit low-spin (LS) to highspin (HS) light-induced conversion at very low temperature. The structural reorganizations related to the light-induced and thermally induced LS-HS transitions were characterized by single-crystal X-ray diffraction below the relaxation temperature (T = 15 K Ͻ T LIESST ) and at 130 K within the thermal hysteresis loop. We show that the LIESST and thermal spin transitions lead to the same structural variations, namely an elongation of the Fe-N bonds by 0.18 Å (Fe-N NCS ) and 0.20 Å (Fe-N btr ), on going from LS to HS, together with a reorientation of the NCS group by nearly 13°. The atomic displacement amplitudes, derived from the crystal structures,

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“…6(a)] and the light-induced hysteresis reported in different system. 31,32,34,41,54 In BIA II, a gradual and homogeneous variation of the spin state is associated with the progressive motion of the Bragg reflections from a purely HS lattice to a purely LS one [see Fig. 6(d)]; such a homogeneous relaxation was observed in another low cooperative spin crossover complex by neutron diffraction.…”

Section: Cooperativity During the Photoconversions And Relaxationsmentioning

confidence: 99%

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

et al. 2012

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We discuss here the important role of intermolecular coupling for the thermal-and light-induced molecular state switching in the solid state. Investigations were performed on the two crystalline polymorphs of the spin-crossover [Fe-(PM-BIA) 2 (NCS) 2 ] material. In addition to structural studies at thermal equilibrium, lightinduced phenomena were investigated through photocrystallography, photomagnetic, and dynamical optical measurements. Strong similarities between the thermal-equilibrium and the out-of-equilibrium light-induced transformations are observed in each polymorph: strong cooperative phenomena in one polymorph versus weak cooperative ones in the second polymorph. These different responses of the two crystalline forms of the compound to external perturbations are discussed at the microscopic level in terms of Ising-like model and two-mode description of on-site molecular potentials.

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Kinetics of light-induced first-order phase transformation in molecular solids:Fe(btr)2(NCS)2∙H2O

Cited by 59 publications

References 20 publications

Multimetastability, phototrapping, and thermal trapping of a metastable commensurate superstructure in a FeIIspin-crossover compound

Multimetastability, phototrapping, and thermal trapping of a metastable commensurate superstructure in a FeIIspin-crossover compound

Optical, Magnetic and Structural Properties of the Spin‐Crossover Complex [Fe(btr)₂(NCS)₂]·H₂O in the Light‐Induced and Thermally Quenched Metastable States

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

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Kinetics of light-induced first-order phase transformation in molecular solids:Fe(btr)2(NCS)2∙H2O

Cited by 59 publications

References 20 publications

Multimetastability, phototrapping, and thermal trapping of a metastable commensurate superstructure in a FeIIspin-crossover compound

Multimetastability, phototrapping, and thermal trapping of a metastable commensurate superstructure in a FeIIspin-crossover compound

Optical, Magnetic and Structural Properties of the Spin‐Crossover Complex [Fe(btr)2(NCS)2]·H2O in the Light‐Induced and Thermally Quenched Metastable States

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

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Optical, Magnetic and Structural Properties of the Spin‐Crossover Complex [Fe(btr)₂(NCS)₂]·H₂O in the Light‐Induced and Thermally Quenched Metastable States