Quasi-one-dimensional (quasi-1D) materials enjoy growing interest due to their unusual physical properties and promise for miniature electronic devices. However, the mechanical exfoliation of quasi-1D materials into thin flakes and nanoribbons received considerably less attention from researchers than the exfoliation of conventional layered crystals. In this study, we investigated the micromechanical exfoliation of representative quasi-1D crystals, TiS3 whiskers, and demonstrate that they typically split into narrow nanoribbons with very smooth, straight edges and clear signatures of 1D TiS3 chains. Theoretical calculations show that the energies required for breaking weak interactions between the two-dimensional (2D) layers and between 1D chains within the layers are comparable and, in turn, are considerably lower than those required for breaking the covalent bonds within the chains. We also emulated macroscopic exfoliation experiments on the nanoscale by applying a local shear force to TiS3 crystals in different crystallographic directions using a tip of an atomic force microscopy (AFM) probe. In the AFM experiments, it was possible to slide the 2D TiS3 layers relative to each other as well as to remove selected 1D chains from the layers. We systematically studied the exfoliated TiS3 crystals by Raman spectroscopy and identified the Raman peaks whose spectral positions were most dependent on the crystals’ thickness. These results could be used to distinguish between TiS3 crystals with thickness ranging from one to about seven monolayers. The conclusions established in this study for the exfoliated TiS3 crystals can be extended to a variety of transition metal trichalcogenide materials as well as other quasi-1D crystals. The possibility of exfoliation of TiS3 into narrow (few-nm wide) crystals with smooth edges could be important for the future realization of miniature device channels with reduced edge scattering of charge carriers.

Abstract.The photon-ion merged-beams technique has been employed at the new PhotonIon spectrometer at PETRA III (PIPE) for measuring multiple photoionization of Xe Absolute cross sections for 3d photoionization of Xe q+ ions (1 ≤ q ≤ 5) 2

Abstract:We describe the application of scattering-type near-field optical microscopy to characterize various semiconducting materials using the electron storage ring Metrology Light Source (MLS) as a broadband synchrotron radiation source. For verifying high-resolution imaging and nano-FTIR spectroscopy we performed scans across nanoscale Si-based surface structures. The obtained results demonstrate that a spatial resolution below 40 nm can be achieved, despite the use of a radiation source with an extremely broad emission spectrum. This approach allows not only for the collection of optical information but also enables the acquisition of nearfield spectral data in the mid-infrared range. The high sensitivity for spectroscopic material discrimination using synchrotron radiation is presented by recording near-field spectra from thin films composed of different materials used in semiconductor technology, such as SiO 2 , SiC, Si x N y , and TiO 2 . ©2014 Optical Society of AmericaOCIS codes: (120.0120) Instrumentation, measurement, and metrology; (180.4243) Near-field microscopy; (240.0240) Optics at surfaces; (300.0300) Spectroscopy; (310.6860) Thin films, optical properties. 1248-1262 (2014). 5. S. Kawata and Y. Inouye, "Scanning probe optical microscopy using a metallic probe tip," Ultramicroscopy 57(2-3), 313-317 (1995). 6. F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, "Scanning interferometric apertureless microscopy: References and linksOptical imaging at 10 angstrom resolution," Science 269(5227), 1083-1085 (1995). 7. R. Bachelot, P. Gleyzes, and A. C. Boccara, "Near-field optical microscope based on local perturbation of a diffraction spot," Opt. Lett. 20(18), 1924-1926 (1995). 8. B. Knoll and F. Keilmann, "Near-field probing of vibrational absorption for chemical microscopy," Nature 399(6732), 134-137 (1999 Helm, "Anisotropy contrast in phonon-enhanced apertureless near-field microscopy using a free-electron laser," Phys. Rev. Lett.

With the predictor problem in mind, we studied in-patients with endogenous depression whether relationships exist among the EEG, the therapeutic response, and the severity of psychopathology. We found that clinically defined responders and non-responders differ in respect of their average power spectra calculated for the two occipital regions. In addition, it was shown that there is a statistically significant correlation between the EEG before treatment and the severity of AMP-documented psychopathology after a 4-week treatment period. This correlation was stronger for the left occipital region than for the right.