{"created":"2023-06-20T13:21:10.684930+00:00","id":1291,"links":{},"metadata":{"_buckets":{"deposit":"05e57a05-0478-4c3d-8c87-df655dc7e3f0"},"_deposit":{"created_by":1,"id":"1291","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"1291"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00001291","sets":["2:432:26"]},"author_link":["10316","10314","10315"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"懐, 平"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"ファイ, ピン"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2000-09-29"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"TTF-CA is a typical mixed-stack charge transfer compound, which undergoes neutral (N) to ionic (I) phase transition by lowering the temperature or applying high pressure.  This N-I phase transition is confirmed to be a first order one and induces various changes in ITF-CA on its structural, optical and magnetic properties.  The low temperature I-phase is characterized by a lattice dimerization along the stacking direction, while the starting N-phase is monomeric and has no dimerization.  Charge transfer (CT) absorption spectral shape in the I-phase has a two-headed structure in contrast to the single-peak one in the N-phase spectra.  Electron spin resonance line shape indicate the creation of a constant spin density below transition temperature, while the dc conductivity data show the evidence of mobile charge carriers at the onset of the I-phase.  Besides the temperature-induced or pressure-induced phase transitions, a photoinduced I-to-N phase transition (PIPT) has also been discovered by using femto-second spectroscopic techniques.  It is found that a macroscopic neutral domain can be generated in the I-phase of TTF-CA by shining a strong laser light of about 0.6eV～2.2eV onto TTF-CA, even when the temperature is very low.  Recent studies on this PIPT reveal that the N-phase generation efficiency quite sensitively depends on the way of the excitation.  For the typical CT excitations, the PIPT has a noticeable threshold excitation intensity, below which the macroscopic neutral domain cannot be generated.  However, for the intramolecular excitations, the N-phase generation efficiency has no significant threshold excitation intensity.  These behaviors reveal the highly nonlinear nature of PIPT.<br />  We present a theoretical work to study this photoinduced I-to-N structural phase transition from a unified point of view.  Using the adiabatic approximation and the mean-field theory, we investigates an extended Peierls-Hubbard model to clarify various features of TTF-CA, ranging from the ground state properties, the absorption spectral shape, to the nonlinear lattice relaxation of the CT exciton.  Our model includes strong infer-molecular Coulomb interactions, which depend nonlinearly on the inter-molecular distance.  A weak infer-chain interaction is also taken into account to describe the formation of the macroscopic neutral domain in the three-dimensional ionic phase.  In the ground state, the quasi-I phase is just below the quasi-N one.  Both these I- and N-phases are locally stable, and a low energy barrier separates them.  In the I-phase, the lattice has 3% dimerization along the stack axis, while the N one is monomeric and has no dimerization.  Based on this mean-field picture, the N-I phase transition in TTF-CA is classified to be the first order.<br />  To calculate the optical absorption spectrum, we have developed a classical Monte-Carlo theory to take the thermal lattice fluctuations into account.  The exciton effect is also included by using the first order perturbation theory.  The resultant spectrum illustrates the peculiar two-headed shape, which agrees with the experimental one.  Thus we could well reproduce the position of these two peaks as well as the relative intensity between them.<br />  By studying the nonlinear lattice relaxation processes of the CT exciton, we have clarified the adiabatic relaxation path, which starts from a Franck-Condom state and terminates up to the large neutral domain formation in the tonic phase.  The ground state energy surface reveals that this neutral domain becomes stable only when its size is large.  Moreover, the first excited state of the neutral domain is little above the Franck-Condom state, and these two states are separated by a high barrier.  Therefore the lowest state of a single CT exciton cannot relax down to the neutral domain straightly, but a large excess energy is necessary so that it can overcome the barrier.  This theoretical result explains the origin of the threshold excitation intensity, below which the macroscopic neutral domain cannot be generated by the photons resonated to the CT exciton.  It has been also discovered that there exist various shallow minima on the energy surface of the ground state.  These minima prevent the fast decay of the neutral domain, and let it have a fairly long lifetime.  We also investigate the anti-phase ionic domain.  This domain is above the neutral one, and a low barrier separates them.  Thus, even if the anti-phase tonic domain is generated just after the photoexcitation, it will soon relax down to the neutral one.  These findings are consistent to the recently obtained time-resolved experimental results.  Furthermore, we illustrate the charge and the spin distributions of the neutral domain.  Our results show that the ground state of the NIDW can carry a unit charge and spin, however, its first excited state can carry almost none of them.  The radiative or nonradiative decay of the excited NIDW is found to be quite difficult, so that, the first excited states can have fairly long lifetime, if we restrict ourselves within the mean-field theory.","subitem_description_type":"Other"}]},"item_1_description_18":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第485号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"数物科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"X1 放射光科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2000"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"HUAI, Ping","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲485_要旨.pdf","filesize":[{"value":"278.3 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨 / Abstract, Screening Result","url":"https://ir.soken.ac.jp/record/1291/files/甲485_要旨.pdf"},"version_id":"61fc3aee-7c45-496e-823f-21288c0251ee"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲485_本文.pdf","filesize":[{"value":"1.9 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/1291/files/甲485_本文.pdf"},"version_id":"bf39a74e-891b-4e2e-89e6-9834d06c8edf"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Ground State, Optical Excited States and Photoinduced Phase Transition in Mixed-Stack Charge Transfer Compound TTF-CA","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Ground State, Optical Excited States and Photoinduced Phase Transition in Mixed-Stack Charge Transfer Compound TTF-CA"},{"subitem_title":"Ground State, Optical Excited States and Photoinduced Phase Transition in Mixed-Stack Charge Transfer Compound TTF-CA","subitem_title_language":"en"}]},"item_type_id":"1","owner":"1","path":["26"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-02-22"},"publish_date":"2010-02-22","publish_status":"0","recid":"1291","relation_version_is_last":true,"title":["Ground State, Optical Excited States and Photoinduced Phase Transition in Mixed-Stack Charge Transfer Compound TTF-CA"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T14:38:31.947069+00:00"}