Scientific Research Division
張石麟博士(2015)
Inclined-incidence hard-X-ray resonator with ultrahigh efficiency and resolution
Y.-H. Wu, Y.-W. Tsai, C.-H. Chu, W.-C. Liu, Y.-Y. Chang, and S.-L. Chang*
Opt. Express 23, 9994 (2015)
We report a high-efficiency hard-X-ray resonator with inclined-incidence geometry. A beam incident at 36.87° with respect to [3 1 0] excites Bragg back diffraction along (12 4 0) at 14.4388 keV for resonance in a Si-based resonator to produce intense resonance fringes. The experimental results showed the visibility enhanced by nearly 30 times compared with normal incidence. Also numerical calculations of the inclined-incidence resonator demonstrate ultrahigh efficiency and extremely narrow resolving power (sub-meV) with low background. This geometry surpasses the intrinsic limits of normal-incidence crystal-based resonators and enables ultrahigh-resolution X-ray optics for X-ray diffraction, spectroscopy, and imaging applications.
吳宇中博士(2015)
Irradiation of Ethylene Diluted in Solid Nitrogen with Vacuum Ultraviolet Light and Electrons: Its Implications for the Formation of HCN and HNC.
H-F Chen, M-C Liu, S-C Chen, T-P Huang, and Y-J Wu,*
Astrophys. J. 804, 36 (2015)
Chemical reactions of C2H4 dispersed in solid nitrogen at 10 K that occur upon irradiation with Lyman- light at a wavelength of 121.6 nm and 500 eV electrons were investigated by measuring the infrared absorption spectra. Photolysis of the matrix samples with 121.6 nm light yielded products, including C2H2, CN, and isomers of C2N2, as well as a pair of HCN and HNC. In contrast, electron bombardment of similar matrix samples mainly resulted in the generation of N3, C2H2, C2H3, C3H2, and C3N−. Mechanisms of the reactions that occur during the photolysis and electron-radiation of the matrix samples are discussed. The results of the study provide insights into the formation of HNC and HCN, as well as nitriles, in N2-rich ice samples containing a small proportion of C2H4.
楊耀文博士(2015)
Damaging Effect of Hot Metal Atoms on Organic Semiconducting Films during Top Contact Formation.
Chia Hsin Wang, Ching-Wen Su, Shen-Wen Chan, Liang-Jen Fan, Ming-Chou Chen, Yaw-Wen Yang*
J. Phys. Chem. C (2015) in press
The formation of a high quality interface between metallic and organic semiconducting thin films is critically important in achieving high-performance organic electronics devices. In this regard, the importance of understanding the multifaceted issue of structure damage incurred to organic films by the evaporated metal atoms cannot be overstated. In the present study, we have investigated the change of a structurally ordered, organic semiconducting (o.s.) thin film of 5,11-bis(triethylsilylethynyl)anthradithiophene (TESADT) effected by gold atoms by means of synchrotron-based soft X-ray spectroscopies including ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopies (XPS) with imaging capability, near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and atomic force microscopy (AFM). This work shows that gold atoms readily diffuse into the organic films and nucleate into nanometer-size clusters, damage chemical structure, destroy structural ordering of the organic films, and shift relevant core level binding energy in accord with the expected interfacial band bending. Additionally, the patterned deposition performed via shadow mask is not reliable in confining Au deposit to the designated region due to the rapid diffusion of Au atoms. As a result, the real Au contacts should be treated as morphologically complicated gold films residing on top of structurally disordered organic film interspersed with Au clusters.
許瑤真博士(2015)
Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atop Alq3
Tu-Ngoc Lam, Yu-Ling Lai, Chih-Han Chen, Po-Hung Chen, Yuet-Loy Chan, Der-Hsin Wei, Hong-Ji Lin, C. T. Chen, Jeng-Han Wang,* Jeng-Tzong Sheu,* and Yao-Jane Hsu*
Phys. Rev. B 91, 041204(R) (2015)
The spin polarization of organic-ferromagnetic interfaces in an organic spin valve critically affects the efficiency of spin injection or detection. We examined the chemical and electronic properties of ferromagnetic Co deposited on organic Alq3 and the interfacial spin-polarized capability of the electronic states. Our x-ray photoemission spectra and calculations with density-functional theory indicate a sequential and unequal distribution of charge from Co clusters to N and then to O atoms in Alq3. The preferential orbital hybridization at specific functional sites produces efficient spin polarization of organic molecules. Element-specific measurements of x-ray magnetic circular dichroism demonstrate the preferential spin polarization in the lowest unoccupied molecular orbital state of N atoms at the complex interface for Co atop Alq3, which agrees satisfactorily with calculation. Our results indicate that an induced interfacial spin polarization on engineering the dominant reaction of Co with mainly N and O atoms in Alq3 might pave a way for effective spin filtering in organic spintronics.