Femtosecond Dynamics of Photoinduced Phase Transitions

光致相变的飞秒动力学

• 批准号: 13304024
• 负责人: SUEMOTO Tohru
• 金额: $ 30.12万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13304024/
• 关键词: femtosecond; time-resolved-luminescence; nickel complex; vanadium bronze; wave-packet; halogen-bridged platinum complex; giant dielectric effect; spin-crossover complex; 核波束; 過渡反射; 白金錯体; ナトリウムヴァナデート; 光誘起現象; コヒーレント励起; 顕微

The ultrafast dynamics of the photoinduce phase transitions has not been well understood before starting this project. We studied the dynamic behavior of these phenomena in pico-and femto-second regions, by using time-resolved luminescence, reflectance and Raman spectroscopy. The materials studied are (1)quasi-one-dimensional platinum complexes, (2)nickel complexes, (3)vanadium bronze, (4)divalent ion spin-cross-over complexes, and (5)quantum paraelectrics.Followings are the main achievements.1.In quasi-one-dimensional halogen-bridged platinum complexes, we investigated the self-trapped excitons, which are important as the intermediate states of photoinduced lattice rearrangements, by using femtosecond luminescence spectroscopy. The motion of the wave-packets is captured as a movie for the first time. Importance of the non-radiative transitions has been revealed, based on the halogen-ion dependence of the decay dynamics.2.In Ni-Br complexes, we found a luminescence with a large Stokes … More shift, which shows the importance of electron-lattice interactions in the excited state, although it has been believed that the electron correlation is more important than the electron-phonon interaction in the ground state.3.We applied femtosecond spectroscopy to the spin ladder system, α'-NaV_2O_5 for the first time. Elementary excitations were coherently generated and a new mode was found near the twice of the spin gap energy. The charge disordering process induced by photo-excitation has been observed as a reflectance change and a response faster than thermal effect was found. Photo-induced phase transition or charge disordering is suggested to be responsible for this phenomenon. These investigations opened the doorway to dynamical studies in this material.4.In spin crossover complexes containing divalent Fe ions, we found a new phase that cannot be produced through thermal process. By tuning the excitation photon energy, specific spin states are generated selectively.5.A giant dielectric response was found in SrTiO_3 and KTaO_3, by irradiating with ultraviolet photons. Less

在开始这个项目之前，光致相变的超快动力学还没有得到很好的理解。我们利用时间分辨发光、反射光谱和拉曼光谱研究了这些现象在皮秒和飞秒波段的动力学行为。本文研究了准一维铂配合物、镍配合物、钒青铜、二价离子自旋交叉配合物和量子顺电材料，主要内容如下：1.在准一维卤素桥铂配合物中，研究了作为光诱导晶格重排中间态的自陷激子，通过使用飞秒发光光谱学。波包的运动首次被捕获为电影。在Ni-Br配合物中，我们发现了一种具有较大Stokes系数的发光 ...更多信息 位移，这表明在激发态电子-晶格相互作用的重要性，虽然人们一直认为电子相关比基态电子-声子相互作用更重要。3.我们首次将飞秒光谱应用于自旋梯系统，即γ ′-NaV_2O_5。相干地产生了基元激发，并在自旋能隙的两倍附近发现了一个新的模式。光激发引起的电荷无序过程表现为反射率的变化，其响应比热效应快，这可能是光致相变或电荷无序引起的。这些研究为该材料的动力学研究打开了大门。4.在含二价铁离子的自旋交叉配合物中，我们发现了一种不能通过热过程产生的新相。通过调节激发光子的能量，可以选择性地产生特定的自旋态。5.在SrTiO_3和KTaO_3中，用紫外光子辐照，发现了巨大的介电响应。少

项目成果

時間分解発光分光法による超高速格子緩和の研究

使用时间分辨发射光谱研究超快晶格弛豫

• 发表时间: 2004
• 期刊: レーザー研究 32
• 作者: 末元徹

Photoindueced phase transition of a spin-crossover complex studied with the combination of SR and laser

SR 和激光相结合研究自旋交叉配合物的光致相变

• 发表时间: 2002
• 期刊: Surface Review and Letters 9
• 作者: K.Takahashi;M.Kamada;Y.Fukui;K.Fukui;T.Tayagaki;K.Tanaka
• 通讯作者: K.Tanaka

L.H.Machtoub, G.El Machtoub, J.Shimoyama, T.Suemoto: "Elementary excitations investigated by femtosecond Raman spectroscopy in underdoped cuprates"Physica C. 392-396. 291-294 (2003)

L.H.Machtoub、G.El Machtoub、J.Shimoyama、T.Suemoto：“通过飞秒拉曼光谱研究欠掺杂铜酸盐的基本激发”Physica C. 392-396。

H.Kamioka, S.Saito, M.Isobe, Y.Ueda, T.Suemoto: "Coherent magnetic oscillation in the spin ladder system α'-NaV_2O_5"Physical Review Letter. 88. 127201-1 (2002)

H.Kamioka、S.Saito、M.Isobe、Y.Ueda、T.Suemoto：“自旋系统阶梯 α-NaV_2O_5 中的相干磁振荡”物理评论信 88. 127201-1 (2002)。

Photoinduced spin transition probed by x-ray diffraction

• DOI: 10.1103/physrevb.69.020101
• 发表时间: 2004-01
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: N. Huby;L. Guérin;E. Collet;L. Toupet;J. Ameline;H. Cailleau;T. Roisnel;T. Tayagaki;Koichiro Tanaka