金沢大学大学院自然科学研究科
研究主要テーマ」として,「(A)時間に依存しないHamilton演算子から得られる分光スペクトル,(B)時間依存のHamilton演算子から得られる質量スペクトル」を考えた。(A)では,主に6種のスペクトル解析((1)有機物のXPS及びXES,(2)Mn_<12>分子磁石の電子状態,(3)交互炭化水素分子の共鳴XES,(4)第二周期元素(C,N,O,F)を含む物質のKVV'のAES),(5)イオン照射により表面改質したキトサンのXPS,(6)炭素同素体のXPS)の追究である。(1)の成果はO,CO,N及びSを含むポリマーについて,共同研究者のKurmaevらによって内外で最初のCKαX線実測スペクトル,更にそのポリマーのCls内殻電子スペクトルを結合エネルギーを精度高く解析した。(2)もKurmaevらとの共同で選択的に注目原子を共鳴XES測定し,理論的解析からMn_<12>O_<12>(CH_3COO)_<16>(H_2O)_4分子のMn_<12>の電子状態を究明した。(3)はC_nH_n分子のab initio MO計算においてLUMOへの1電子励起中間状態を考慮し,その分子の共鳴XESを解析した。(4)の研究「第二周期元素(C,N,O,F)を含む物質のオージェ電子スペクトル(AES)の解析」はAESのエネルギー計算に関して、新しい算出法を提唱した。実例としてグラファイトのC,GaNのN,SiO_2のO及びLiFのFに関するオージェ電子スペクトルの解析結果を示した。(5)は理大グループとの共同でKr^+イオン照射による表面改質キトサンのXPSスペクトルを量子分子動力学による熱分解した断片物質のXPSスペクトルと対比し,イオン照射後の表面状態を明らかにした。(6)はプラズマ蒸着法などで作製されたdiamond-like-carbon(DLC)関してダイヤモンド/グラファイトの相対比を価電子帯スペクトル解析から判別する方法を提唱した。更に同素体の仕事関数はカーボンナノチューブ<グラファイト<ダイヤモンド<C60の順に大きいことを示した。これらは論文として投稿し、受理された。また(B)では量子分子動力学プログラムの改良(ab initio MOプログラムとMDプログラムをドッキング更に励起状態を含めたMOプログラムとMDプログラムをドッキング)し、(1)ポリマー,フラーレン及び有機分子などの熱分解をシミュレーションした。(2)リグニンモノマー及びダイマーと(3)ポリマー(PS及びPET)のSIMSによる質量スペクトルをそれぞれモデル分子の熱分解をシミュレーションし、TOF-SIMSによる有機物の質量スペクトルと対比させた。これらも論文として投稿し受理された。その他,量子波束ダイナミクスによる系のダイナミクスを波束の動きで可視化した研究,固体NMRによる相転移物質などの分子ダイナミクスを追究した。
We considered from two theoretical viewpoints of both (A) time-independent and (B) time-dependent Hamiltonian for the development of theoretical surface spectral apparatus, in order to simulate electron spectra of substances by surface scientific instruments, and to gain the mass spectra by MS and static or TOF SIMS, respectively.In (A), six kinds of spectral analyses were performed in the following way; (1) X-Ray Photoelectron and Carbon Kα Emission measurements and calculations of O-, CO-, N-, and S-containing Substances (The combined analysis of valence XPS and carbon Ka XES for PEO, PVA, PVME, PVMK, PET, P4VP, PAO, PPS polymers was performed to determine the individual contributions from pσ-, and pπ-bonding molecular orbitals of the polymers by DFT calculations. We calculated all CEBEs of the model molecules using the ΔE_ks approach. Our simulated Cls photoelectron and C Kα emission spectra are in good agreement with our measurements.), (2)Electronic structure of a Mn_12 molecular magnet: Theory and experiment, (3)Simulation of resonant X-ray emission spectra of ethylene and benzene molecules (We proposed a theoretical method for analysis of resonant X-ray emission spectra from ab initio MO calculation using single configuration approximation as an intermediate state.) (4)Theoretical analysis of Auger electron spectra of 2nd periodic element containing substances(Simulated AES and valence XES of four substances [graphite, GaN, SiO_2, LiF] by DFT calculations using model molecules are in considerably good accordance with the experimental ones. Experimental AES of the substances were classified in each range of 1s-2s2s, 1s-2s2p and 1s-2p2p transitions for C, N, 0 and F KVV' spectra, respectively.), (5)XPS Spectral Simulation of Chitosan in Thermal Decomposition Process (6)X-Ray Photoelectron Spectral Analysis for Carbon Allotropes (We performed DFT calculations using Amsterdam density functional (ADF) program to simulate X-ray photoelectron spectra for carbon allotropes (diamond, graphite, single-wall carbon nanotube(SWCN), and fullerene C_60). We firstly described the simulation method for valence electron spectra to distinguish the diamond phase of carbon from the graphite carbon, and secondly evaluated the WD values from the differences between the calculated core-electron binding energies(CEBE)s of the model molecules (using ΔE_ks approach(like ΔSCF method in MO))and experimental CEBEs of carbon allotropes. The WD values of carbon allotropes correspond to the order of experimental values (CNT < graphite < diamond < C_<60>) for work functions obtained from accurate cylindrical analyzer(CMA)detector by Goto's and co-workers.)In (B), three investigations were performed as follows; (1) Simulations of thermal decomposition for carbon allotrope molecules by a quantum molecular dynamics method (In order to simulate thermal decomposition of carbon allotrope molecules [single walled carbon nanotube(SWNT)models{arm-chair(C_<54>H_<12>), zigzag(C_<50>H_<10>) types), C_<60>, and graphic model C_<42>H_<16>], we used MD with semi-empirical AM1 MO method(a kind of QMD).) (2)Simulation of SIMS for monomer and dimer of lignin under the assumption of thermal decomposition using QMD method(The thermal decomposition of the monomer and dimer of lignin has been simulated by quantum molecular dynamics(DMD) method. We obtained the thermally decomposed fragments with positive, neural and negative changes from SCF MO calculation at each data of the last MD step, and simulated the fragment distribution of the monomer and dimer lignins from the last step in 30〜40 runs. Simulated mass numbers of positively and negatively charged fragments for lignin monomer and dimer showed considerably good accordance with the experimental results in TOF-SIMS observed by Saito and co-workers.), (3)Fragments Distribution of Thermal Decomposition for PS and PET with QMD Calculations by Considering the Excited and Charged Model Molecules(Simulations by a quantum molecular dynamics(QMD) (MD with MO) method were demonstrated on the thermal decomposition of PS and PET polymers using the model molecules at the ground state including excited and positive charged states. The calculated neutral, positive and negative fragment distributions of PS and PET models with 0.82 eV energy control were obtained as (93.5, 2.3, and 4.3%), and(87.8, 5.3, and 6.9%) to the total fragments, respectively. The ratios seem to correspond well to the values observed experimentally in SIMS.).
研究課題/領域番号:18550013, 研究期間(年度):2006 – 2007
出典：研究課題「理論的表面分光装置の開発」課題番号18550013（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-18550013/185500132007kenkyu_seika_hokoku_gaiyo/）を加工して作成