Development of Optically-coupled Scanning Tunneling Microscope for Investigation of Multi-pulse Laser Induced Defect States and Time Resolved Dynamics PDF Download
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Author: Ryan James Rodriguez
Publisher:
ISBN:
Category : Femtosecond lasers
Languages : en
Pages : 0
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Book Description
Ultra-Fast Scanning Tunneling Microscopy (UFSTM) is a novel imaging technique that uses high intensity femtosecond laser light to generate atomic defect states called "traps" and provide subsequent atomic surface imaging between pulses. Many surface engineering applications are possible through femtosecond laser induced damage (fs-LID), a process where a strong non-perturbing laser electric field generates a high density of charge carriers that eventually thermalize and impart energy into a material's lattice changing the surface morphology. The number of pulses during illumination plays a large role in the resulting morphology with current theory predicting the formation of trap states in-between pulses. The trap states are too subtle to observe using traditional methods (ie. scanning electron microscopy or optical based microscopy). This thesis presents a coordinated effort in developing a novel scanning tunneling microscope system capable of detecting atomic trap states. In particular, a discussion of the instrumentation challenges associated with UFSTM techniques are presented. This work also includes a brief summary of the X-ray STM imaging technique that can also be used for elemental resolved surface imaging. The instrumentation challenges associated with coupling x-ray light with a standard STM system is included.
Author: Ryan James Rodriguez
Publisher:
ISBN:
Category : Femtosecond lasers
Languages : en
Pages : 0
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Book Description
Ultra-Fast Scanning Tunneling Microscopy (UFSTM) is a novel imaging technique that uses high intensity femtosecond laser light to generate atomic defect states called "traps" and provide subsequent atomic surface imaging between pulses. Many surface engineering applications are possible through femtosecond laser induced damage (fs-LID), a process where a strong non-perturbing laser electric field generates a high density of charge carriers that eventually thermalize and impart energy into a material's lattice changing the surface morphology. The number of pulses during illumination plays a large role in the resulting morphology with current theory predicting the formation of trap states in-between pulses. The trap states are too subtle to observe using traditional methods (ie. scanning electron microscopy or optical based microscopy). This thesis presents a coordinated effort in developing a novel scanning tunneling microscope system capable of detecting atomic trap states. In particular, a discussion of the instrumentation challenges associated with UFSTM techniques are presented. This work also includes a brief summary of the X-ray STM imaging technique that can also be used for elemental resolved surface imaging. The instrumentation challenges associated with coupling x-ray light with a standard STM system is included.
Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 2540
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5
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Book Description
At the end of three years, we have met the majority of the project goals and made significant progress on the few remaining issues. As outlined in more detail below, we have designed and built a UHV system and incorporated a commercially made, custom designed STM. The microscope has demonstrated atomic resolution. We have a femtosecond laser system, optics for delivering ultrafast laser pulses to the STM, and a computer controlled delay line for time-resolved measurements. This project also has funding from the National Science Foundation, and work continues with that funding while we actively seek additional funds for continued work. We are actively working to develop the instrument as a probe-station for molecular electronics. To that end, we are collaborating with Prof. David Glueck in the Chemistry department on time-domain investigations of Coulomb-blockade effects in Au nanoparticles.
Author: Philipp Kloth
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In this thesis, the successful implementation of optical excitation for time-resolved Scanning Tunneling Microscopy (STM) is presented. The fruitful combination of these two experimental methods allows investigating photo-induced dynamic processes on the nanosecond time scale with atomic resolution. The optical setup provides a great versatility regarding the adjustment of excitation parameters such as optical pulse height, pulse width or pulse repetition rate to the experimental needs. Moreover, for the first time, it is possible to disentangle and quantify thermally induced effects, e.g. ...
Author: Klaus D. Sattler
Publisher: CRC Press
ISBN: 1351260553
Category : Science
Languages : en
Pages : 4153
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Book Description
This 21st Century Nanoscience Handbook will be the most comprehensive, up-to-date large reference work for the field of nanoscience. Handbook of Nanophysics, by the same editor, published in the fall of 2010, was embraced as the first comprehensive reference to consider both fundamental and applied aspects of nanophysics. This follow-up project has been conceived as a necessary expansion and full update that considers the significant advances made in the field since 2010. It goes well beyond the physics as warranted by recent developments in the field. Key Features: Provides the most comprehensive, up-to-date large reference work for the field. Chapters written by international experts in the field. Emphasises presentation and real results and applications. This handbook distinguishes itself from other works by its breadth of coverage, readability and timely topics. The intended readership is very broad, from students and instructors to engineers, physicists, chemists, biologists, biomedical researchers, industry professionals, governmental scientists, and others whose work is impacted by nanotechnology. It will be an indispensable resource in academic, government, and industry libraries worldwide. The fields impacted by nanoscience extend from materials science and engineering to biotechnology, biomedical engineering, medicine, electrical engineering, pharmaceutical science, computer technology, aerospace engineering, mechanical engineering, food science, and beyond.
Author: Seizo Morita
Publisher: Springer Science & Business Media
ISBN: 3540343156
Category : Technology & Engineering
Languages : en
Pages : 207
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Book Description
Scanning tunneling microscopy has achieved remarkable progress and become the key technology for surface science. This book predicts the future development for all of scanning probe microscopy (SPM). Such forecasts may help to determine the course ultimately taken and may accelerate research and development on nanotechnology and nanoscience, as well as all in SPM-related fields in the future.
Author: Chunli Bai
Publisher: Springer Science & Business Media
ISBN: 9783540657156
Category : Medical
Languages : en
Pages : 392
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Book Description
This book presents a unified view of the rapidly growing field of scanning tunneling microscopy and its many derivatives. After examining novel scanning-probe techniques and the instrumentation and methods, the book provides detailed accounts of STM applications. It examines limitations of the present-day investigations and provides insight into further trends. "I strongly recommend that Professor Bai's book be a part of any library that serves surface scientists, biochemists, biophysicists, material scientists, and students of any science or engineering field...There is no doubt that this is one of the better (most thoughtful) texts." Journal of the American Chemical Society (Review of 1/e)
Author: Mikio Yamashita
Publisher: Springer
ISBN: 3540271406
Category : Technology & Engineering
Languages : en
Pages : 400
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Book Description
Deals with both the ultrashort laser-pulse technology in the few- to mono-cycle region and the laser-surface-controlled scanning-tunneling microscopy (STM) extending into the spatiotemporal extreme technology. The former covers the theory of nonlinear pulse propagation beyond the slowly-varing-envelope approximation, the generation and active chirp compensation of ultrabroadband optical pulses, the amplitude and phase characterization of few- to mono-cycle pulses, and the feedback field control for the mono-cycle-like pulse generation. In addition, the wavelength-multiplex shaping of ultrabroadband pulses, and the carrier-phase measurement and control of few-cycle pulses are described. The latter covers the CW-laser-excitation STM, the femtosecond-time-resolved STM and atomic-level surface phenomena controlled by femtosecond pulses.
Author: Suchit Sharma
Publisher: GRIN Verlag
ISBN: 3668588252
Category : Technology & Engineering
Languages : en
Pages : 21
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Book Description
Literature Review from the year 2015 in the subject Engineering - General, Indian Institute of Technology, Delhi, course: Mineral Engineering, language: English, abstract: Atomic-scale resolution is needed to study the arrangement of atoms in materials and advancing their understanding. Since the seventeenth-century optical microscopes using visible light as illumination source have led our quest to observe microscopic species but the resolution attainable reached physical limits due to the much longer wavelength of visible light. After the discovery of wave nature associated with particle bodies, a new channel of thought opened considering much shorter wavelength of particles and their special properties when interacting with the sample under observation. These particles i.e. electrons, neutrons and ions were developed in different techniques and were used as illumination sources. Herein, the development of scanning tunneling microscopy which used electrons to uncover irregularities in the arrangement of atoms in thin materials via the quantum mechanical phenomenon of electron tunneling became a sensational invention. Atomic Force Microscopy (AFM) is a development over STM which relied on measuring the forces of contact between the sample and a scanning probe which overcame the earlier technique only allowing conductors or pretreated surfaces for conducting to be observed. Since measuring contact forces between materials is a more fundamental approach that is equally but more sensitive than measuring tunneling current flowing between them, atomic force microscopy has been able to image insulators as well as semiconductors and conductors with atomic resolution by substituting tunneling current with an atomic contact force sensing arrangement, a delicate cantilever, which can image conductors and insulators alike via mechanical "touch" while running over surface atoms of the sample. AFM has seen a massive proliferation in hobbyistâs lab in form of ambient-condition scanning environment as opposed to an ultra-high vacuum of sophisticated labs and self-assembled instrumentations. The success of ATM as a cost-effective imaging tool with dramatically increased ease of conceptual understanding and use particularly with the assistance of significant computing power in the form of personal computers which offsets the computational difficulty of resolving experimental information which makes up for physical simplicity of instrument design has seen its proliferation to numerous labs in universities and technology companies worldwide.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 74
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Book Description
I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM's atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.
