Photoinduced nucleation theory in one-dimensional systems

2008

Phys. Rev. Lett.

Nonlinear dynamics of photoinduced cooperative phenomena is studied by numerical calculations on a model of molecular crystals. We found that the photoinduced nucleation process is triggered only when certain amount of excitation energy is supplied in a narrow part of the system, i.e., there exists a smallest cluster of excited molecules which makes the nucleation possible. As a result, the portion of the cooperatively converted molecules is nonlinearly dependent on the photoexcitation strength, which has been observed in various materials.

mentioning

confidence: 99%

Nonlinearity in the Dynamics of Photoinduced Nucleation Process

2008

Phys. Rev. Lett.

“…We stress that, contrary to the one-dimensional case [8], the domain growth by successive conversion of the molecules does not take place in higher dimensional cases if intermolecular interactions other than vibrational coupling α is neglected. This is a particular property in higher dimensional systems, since it was pointed out that the converted domain grows only by the intermolecular interaction between molecular distortion [8].…”

Section: Discussionmentioning

confidence: 77%

“…This is a particular property in higher dimensional systems, since it was pointed out that the converted domain grows only by the intermolecular interaction between molecular distortion [8]. In general, the value of α should be less 1/M where M is the coordination number of the lattice.…”

Section: Discussionmentioning

confidence: 99%

“…These photoinduced cooperative phenomena are considered to have a common mechanism, and many experimental and/or theoretical studies have been presented to make it clear [7,8,9]. In particular, when we are interested in controlling such cooperativity by designed optical pulses, it is necessary to understand the transient properties of the photoinduced cooperative phenomena more deeply.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coherent dynamics of photoinduced nucleation processes

2007

Phys. Rev. B

We study the dynamics of initial nucleation processes of photoinduced structural change of molecular crystals. In order to describe the nonadiabatic transition in each molecule, we employ a model of localized electrons coupled with a fully quantized phonon mode, and the time-dependent Schrödinger equation for the model is numerically solved.We found a minimal model to describe the nucleation induced by injection of an excited state of a single molecule in which multiple types of intermolecular interactions are required. In this model coherently driven molecular distortion plays an important role in the successive conversion of electronic states which leads to photoinduced cooperative phenomena.

“…These photoinduced cooperative phenomena in condensed matter have brought us fruitful theoretical and experimental problems with nonequilibrium dynamics of excited states, and many studies have been presented to clarify their mechanism[8, 9,10,11,12,13]. In particular, coherent dynamics of the photoinduced cooperative phenomena is relevant to control such cooperativity by designed optical pulses.…”

Section: Introductionmentioning

confidence: 99%

Quantum pattern formation dynamics of photoinduced nucleation

2008

Phys. Rev. B

We study the dynamics of quantum pattern formation processes in molecular crystals which is a concomitant with photoinduced nucleation. Since the nucleation process in coherent regime is driven by the nonadiabatic transition in each molecule followed by the propagation of phonons, it is necessary to take into account the quantum nature of both electrons and phonons in order to pursue the dynamics of the system. Therefore, we employ a model of localized electrons coupled with a quantized phonon mode and solved the time-dependent Schrödinger equation numerically.We found that there is a minimal size of clusters of excited molecules which triggers the photoinduced nucleation process, i.e., nucleation does not take place unless sufficient photoexcitation energy is concentrated within a narrow area of the system. We show that this result means that the spatial distribution of photoexcited molecules plays 1 an important role in the nonlinearity of the dynamics and also of the optical properties observed in experiments. We calculated the conversion ratio, the nucleation rate, and correlation functions to reveal the dynamical properties of the pattern formation process, and the initial dynamics of the photoinduced structural change is discussed from the viewpoint of pattern formation.