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Статті в журналах з теми "Pump-Probe device":
1
Yuan, Chao, Riley Hanus, and Samuel Graham. "A review of thermoreflectance techniques for characterizing wide bandgap semiconductors’ thermal properties and devices’ temperatures." Journal of Applied Physics 132, no. 22 (December 14, 2022): 220701. http://dx.doi.org/10.1063/5.0122200.
Анотація:
Thermoreflectance-based techniques, such as pump–probe thermoreflectance (pump–probe TR) and thermoreflectance thermal imaging (TTI), have emerged as the powerful and versatile tools for the characterization of wide bandgap (WBG) and ultrawide bandgap (UWBG) semiconductor thermal transport properties and device temperatures, respectively. This Review begins with the basic principles and standard implementations of pump–probe TR and TTI techniques, illustrating that when analyzing WBG and UWBG materials or devices with pump–probe TR or TTI, a metal thin-film layer is often required. Due to the transparency of the semiconductor layers to light sources with sub-bandgap energies, these measurements directly on semiconductors with bandgaps larger than 3 eV remain challenging. This Review then summarizes the general applications of pump–probe TR and TTI techniques for characterizing WBG and UWBG materials and devices where thin metals are utilized, followed by introducing more advanced approaches to conventional pump–probe TR and TTI methods, which achieve the direct characterizations of thermal properties on GaN-based materials and the channel temperature on GaN-based devices without the use of thin-film metals. Discussions on these techniques show that they provide more accurate results and rapid feedback and would ideally be used as a monitoring tool during manufacturing. Finally, this Review concludes with a summary that discusses the current limitations and proposes some directions for future development.
2
Zhong, Haoyuan, Changhua Bao, Tianyun Lin, Shaohua Zhou, and Shuyun Zhou. "A newly designed femtosecond KBe2BO3F2 device with pulse duration down to 55 fs for time- and angle-resolved photoemission spectroscopy." Review of Scientific Instruments 93, no. 11 (November 1, 2022): 113910. http://dx.doi.org/10.1063/5.0106864.
Анотація:
Developing a widely tunable vacuum ultraviolet (VUV) source with a sub-100 fs pulse duration is critical for ultrafast pump–probe techniques such as time- and angle-resolved photoemission spectroscopy (TrARPES). While a tunable probe source with a photon energy of 5.3–7.0 eV has been recently implemented for TrARPES by using a KBe2BO3F2 (KBBF) device, the time resolution of 280–320 fs is still not ideal, which is mainly limited by the duration of the VUV probe pulse generated by the KBBF device. Here, by designing a new KBBF device, which is specially optimized for fs applications, an optimum pulse duration of 55 fs is obtained after systematic diagnostics and optimization. More importantly, a high time resolution of 81–95 fs is achieved for TrARPES measurements covering the probe photon energy range of 5.3–7.0 eV, making it particularly useful for investigating the ultrafast dynamics of quantum materials. Our work extends the application of the KBBF device to ultrafast pump–probe techniques with the advantages of both a widely tunable VUV source and ultimate time resolution.
3
Nango, Eriko, Minoru Kubo, Kensuke Tono, and So Iwata. "Pump-Probe Time-Resolved Serial Femtosecond Crystallography at SACLA: Current Status and Data Collection Strategies." Applied Sciences 9, no. 24 (December 14, 2019): 5505. http://dx.doi.org/10.3390/app9245505.
Анотація:
Structural information on protein dynamics is a critical factor in fully understanding the protein functions. Pump-probe time-resolved serial femtosecond crystallography (TR-SFX) is a recently established technique for visualizing the structural changes or reactions in proteins that are at work with high spatial and temporal resolution. In the pump-probe method, protein microcrystals are continuously delivered from an injector and exposed to an X-ray free-electron laser (XFEL) pulse after a trigger to initiate a reaction, such as light, chemicals, temperature, and electric field, which affords the structural snapshots of intermediates that occur in the protein. We are in the process of developing the device and techniques for pump-probe TR-SFX while using XFEL produced at SPring-8 Angstrom Compact Free-Electron Laser (SACLA). In this paper, we described our current development details and data collection strategies for the optical pump X-ray probe TR-SFX experiment at SACLA and then reported the techniques of in crystallo TR spectroscopy, which is useful in clarifying the nature of reaction that takes place in crystals in advance.
4
Kubo, Minoru, Eriko Nango, Kensuke Tono, Tetsunari Kimura, Shigeki Owada, Changyong Song, Fumitaka Mafuné, et al. "Nanosecond pump–probe device for time-resolved serial femtosecond crystallography developed at SACLA." Journal of Synchrotron Radiation 24, no. 5 (August 22, 2017): 1086–91. http://dx.doi.org/10.1107/s160057751701030x.
Анотація:
X-ray free-electron lasers (XFELs) have opened new opportunities for time-resolved X-ray crystallography. Here a nanosecond optical-pump XFEL-probe device developed for time-resolved serial femtosecond crystallography (TR-SFX) studies of photo-induced reactions in proteins at the SPring-8 Angstrom Compact free-electron LAser (SACLA) is reported. The optical-fiber-based system is a good choice for a quick setup in a limited beam time and allows pump illumination from two directions to achieve high excitation efficiency of protein microcrystals. Two types of injectors are used: one for extruding highly viscous samples such as lipidic cubic phase (LCP) and the other for pulsed liquid droplets. Under standard sample flow conditions from the viscous-sample injector, delay times from nanoseconds to tens of milliseconds are accessible, typical time scales required to study large protein conformational changes. A first demonstration of a TR-SFX experiment on bacteriorhodopsin in bicelle using a setup with a droplet-type injector is also presented.
5
Guiraudon, Gerard M., Douglas L. Jones, Daniel Bainbridge, John T. Moore, Chris Wedlake, Cristian Linte, Andrew Wiles, and Terry M. Peters. "Off-Pump Atrial Septal Defect Closure Using the Universal Cardiac Introducer®." Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 4, no. 1 (January 2009): 20–26. http://dx.doi.org/10.1097/imi.0b013e31819878f2.
Анотація:
Objective Optimal atrial septal defect (ASD) closure should combine off-pump techniques with the effectiveness and versatility of open-heart techniques. We report our experience with off-pump ASD closure using the Universal Cardiac Introducer (UCI) in a porcine model. The goal was to create an ASD over the fossa ovale (FO) and position a patch over the ASD under ultrasound (US) imaging and augmented virtual reality guidance. Methods An US probe (tracked with a magnetic tracking system) was positioned into the esophagus (transesophageal echocardiographic probe) for real-time image-guidance. The right atrium (RA) of six pigs was exposed via a right lateral thoracotomy or medial sternotomy. The UCI was attached to the RA wall. A punching tool was introduced via the UCI, navigated and positioned, under US guidance, to create an ASD into the FO. A patch with its holder and a stapling device were introduced into the RA via the UCI. The patch was positioned on the ASD. Occlusion of the ASD was determined using US and Doppler imaging. Results The FO membrane was excised successfully in all animals. US image-guidance provided excellent visualization. The patch was positioned in all cases with complete occlusion of the ASD. The stapling device proved too bulky, impeding circumferential positioning. Conclusions Using the UCI, ASD closure was safe and feasible. US imaging, combined with virtual and augmented reality provided accurate navigating and positioning. This study also provided valuable information on the future design of anchoring devices for intracardiac procedures.
6
Wang, Cong, Lingfeng Gao, Hualong Chen, Yiquan Xu, Chunyang Ma, Haizi Yao, Yufeng Song, and Han Zhang. "Broadband and ultrafast all-optical switching based on transition metal carbide." Nanophotonics 10, no. 10 (June 25, 2021): 2617–23. http://dx.doi.org/10.1515/nanoph-2021-0066.
Анотація:
Abstract Ultrafast all-optical switches have attracted considerable attention for breaking through the speed limitation of electric devices. However, ultrafast and high-efficiency all-optical switches based on two-dimensional (2D) materials can be achieved due to their strong nonlinear optical response and ultrafast carrier dynamic. For this reason, we propose the pump-probe method to achieve an ultrafast optical switcher with a response time of 192 fs and a switching energy of 800 nJ by using transition metal carbide (Nb2C). The response time and switching energy are far smaller than that of the all-optical device based on the saturable absorption effect of 2D materials. It is believed that the Nb2C-based all-optical switch provides a novel idea to achieve a high-performance all-optical device and has the potential for application in high-speed photonics processing.
7
Lim, Swee Sien, David Giovanni, Qiannan Zhang, Ankur Solanki, Nur Fadilah Jamaludin, Jia Wei Melvin Lim, Nripan Mathews, Subodh Mhaisalkar, Maxim S. Pshenichnikov, and Tze Chien Sum. "Hot carrier extraction in CH3NH3PbI3 unveiled by pump-push-probe spectroscopy." Science Advances 5, no. 11 (November 2019): eaax3620. http://dx.doi.org/10.1126/sciadv.aax3620.
Анотація:
Halide perovskites are promising materials for development in hot carrier (HC) solar cells, where the excess energy of above-bandgap photons is harvested before being wasted as heat to enhance device efficiency. Presently, HC separation and transfer processes at higher-energy states remain poorly understood. Here, we investigate the excited state dynamics in CH3NH3PbI3 using pump-push-probe spectroscopy. It has its intrinsic advantages for studying these dynamics over conventional transient spectroscopy, albeit complementary to one another. By exploiting the broad excited-state absorption characteristics, our findings reveal the transfer of HCs from these higher-energy states into bathophenanthroline (bphen), an energy selective organic acceptor far above perovskite’s band edges. Complete HC extraction is realized only after overcoming the interfacial barrier formed at the heterojunction, estimated to be between 1.01 and 1.08 eV above bphen’s lowest unoccupied molecular orbital level. The insights gained here are essential for the development of a new class of optoelectronics.
8
Sander, Mathias, Roman Bauer, Victoria Kabanova, Matteo Levantino, Michael Wulff, Daniel Pfuetzenreuter, Jutta Schwarzkopf, and Peter Gaal. "Demonstration of a picosecond Bragg switch for hard X-rays in a synchrotron-based pump–probe experiment." Journal of Synchrotron Radiation 26, no. 4 (June 12, 2019): 1253–59. http://dx.doi.org/10.1107/s1600577519005356.
Анотація:
A benchmark experiment is reported that demonstrates the shortening of hard X-ray pulses in a synchrotron-based optical pump–X-ray probe measurement. The pulse-shortening device is a photoacoustic Bragg switch that reduces the temporal resolution of an incident X-ray pulse to approximately 7.5 ps. The Bragg switch is employed to monitor propagating sound waves in nanometer thin epitaxial films. From the experimental data, the pulse duration, diffraction efficiency and switching contrast of the device can be inferred. A detailed efficiency analysis shows that the switch can deliver up to 109 photons s−1 in high-repetition-rate synchrotron experiments.
9
Johnson, Howard D., Marc S. Morgan, and Joe R. Utley. "Use of the Cell Saver as a Rapid Infusion Device." Journal of ExtraCorporeal Technology 21, no. 3 (September 1989): 96–99. http://dx.doi.org/10.1051/ject/198921396.
Анотація:
A Bio-Medicus pump with a model BP 80, flow probe, model DP 38, and Gott TDMAC Shunt tubing, primed with Plasma Lyte A, pH 7.4, was used during a repair of a descending aortic aneurysm. The Haemonetic Cell Saver Plus with 1/4" tubing, List #243, and Gish Cardiotomy ATR-2900F was used to process shed blood. The patient was heparinized with 31,000 units of beef lung heparin (400 units/Kg) to maintain the activated clotting time above 480 seconds. The aneurysm was opened. Collateral bleeding caused the patient to bleed out excessively into the cell saver, rendering the Bio-Pump ineffective due to severe hypovolemia. As the bleeding was controlled, the cell saver was connected to the Gott TDMAC shunt tubing with a 1/4" X 3/8" connector to autotransfuse shed blood from the cardiotomy back to the patient, bypassing the cell saver centrifuge. The aortic cross clamp time was 22 minutes. The patient suffered no complications and at the 12 month follow up, she continues to do well. In summary, we feel that the surgical team should be equipped to provide ancillary support as the situation requires.
10
Zaman, Abdullah M., Yuichi Saito, Yuezhen Lu, Farhan Nur Kholid, Nikita W. Almond, Oliver J. Burton, Jack Alexander-Webber, et al. "Ultrafast modulation of a THz metamaterial/graphene array integrated device." Applied Physics Letters 121, no. 9 (August 29, 2022): 091102. http://dx.doi.org/10.1063/5.0104780.
Анотація:
We report on the ultrafast modulation of a graphene loaded artificial metasurface realized on a SiO2/Si substrate by near-IR laser pump, detected via terahertz probe at the resonant frequency of ∼0.8 THz. The results have been acquired by setting the Fermi energy of graphene at the Dirac point via electrostatic gating and illuminating the sample with 40 fs pump pulses at different fluences, ranging from 0.9 to 0.018 mJ/cm2. The sub-ps conductivity rising time was attributed to the combined effect of the ultrafast generation of hot carriers in graphene and electron–hole generation in silicon. In correspondence of the resonance, it was possible to clearly distinguish a partial recovery time of ∼2 ps mainly due to carrier-phonon relaxation in graphene, superimposed to the > 1 ns recovery time of silicon. The resonant metasurface yielded ∼6 dB modulation depth in E-field amplitude at 0.8 THz for the range of fluences considered. These measurements set an upper limit for the reconfiguration speed achievable by graphene-based terahertz devices. At the same time, this work represents a great progress toward the realization of an ultrafast THz optoelectronic platform for a plethora of applications, ranging from the investigation of the ultrastrong light-matter regime to the next generation wireless communications.
Дисертації з теми "Pump-Probe device":
1
Pintossi, C. "CARBON-BASED HYBRID PLATFORMS FOR NOVEL PHOTOVOLTAIC DEVICES: BURIED INTERFACE CHEMISTRY AND CHARGE CARRIERS DYNAMICS." Doctoral thesis, Università degli Studi di Milano, 2016. http://hdl.handle.net/2434/362241.
Анотація:
Current photovoltaic (PV) market is strongly dominated by an intense use of silicon. Although it is the second most abundant element on the Earth crust, after oxygen, Si is never present in its pure form but always bounded with other elements, and relatively complex and expensive purification procedures are needed in order to have clean, crystalline and optimally doped pure silicon.
This issue, joined with the ever-increasing demand of clean Si by almost all the technological modern applications, led scientists all over the world to look for suitable alternatives.
One of the most promising options, is to try to substitute silicon with carbon, essentially for two reasons: (i) pure C not only exists in nature but can also be obtained and purified through easy and low-cost processes, (ii) carbon can behave as a metal or a semiconductor without being doped, depending only on the particular allotrope.
Moreover, carbon allotropes capability of arranging in various geometry allows C-based materials to assume different dimensionality, starting from the quasi zero-dimensional fullerene to three-dimensional diamonds. This makes carbon nanomaterials excellent candidate for a wide range of electrical and technological devices, offering the possibility to chose the suitable allotropes depending on the particular task that is needed to be fulfilled.
For photovoltaic application, a semiconducting material which can provide dissociation sites for excitons is necessary. To accomplish this role, the mono-dimensional form of C, carbon nanotubes (CNTs), revealed to be a perfect substitute of p-type silicon, on one side of the junction because CNTs are naturally p-doped in air.
Moreover, thanks to their peculiar geometry and extraordinary electrical conductivity, they are able to provide excellent transport path for the dissociated carriers with a very good transparency (which allows a relevant amount of incident light to reach the depletion region).
In the first chapter of this thesis, carbon nanotubes will be introduced, emphasizing the properties which make this nanostructured materials optimal for PV applications. Then, the different types of carbon/silicon heterojunctions will be analyzed, starting from the classical semiconductor theory, to a more complex and realistic model. At the end of the chapter CNTs solar cells state of the art will be presented, highlighting the open questions at which this thesis is aimed to answer.
The experimental techniques, such as angle-resolved X-rays photoelectron spectroscopy (AR-XPS) and transient reflectivity (TR) measurements, used to reach this goal will be presented in Chapter 2, together with the description of the manufacturing processes that yielded to the creation of three different series of PV devices, with an improvement of the efficiency from 0.1% to 12.2% in three years.
In the third chapter, we will show how the complex buried interface between CNTs and Si can be investigated and modelled by means of photoelectron spectroscopy techniques. A complex oxide interface, composed by silicon dioxide and non-stoichiometric silicon oxide, has been unveiled and possible effects on the power conversion efficiency of PV devices are outlined.
A systematic study on the chemical and physical properties of the buried interface will be presented in Chapter 4. Oxides have been alternatively removed and regrown using suitable acids and the effects on the PV performances will be discussed in detail in this chapter. The doping effects of acids on the carbon nanotubes will also be investigated through Raman spectroscopy.
Acid effects on the heterojunctions will be unambiguously shown by the XPS measurements, and the matching of these data with the electrical PV measurements allows us to discuss the nature of the heterojunction in more detail.
In order to properly address the operation mechanism of these devices, which can be either a conventional p-n or a metal-insulator-semiconductor (MIS) junction, the dynamics of charge transfer processes at the interface will be investigated in Chapter 5 with time-resolved pump-probe reflectivity measurement.
The aim is to find a correlation between the thickness of the buried SiOxlayer and the carriers photogeneration and transport, comparing the device electrical parameter with the ultrafast behavior, analyzed by time-resolved reflectivity.
These last findings, along with several improvements in the CNTs dispersion and deposition, have led to the creation of optimized third-series solar cells with a record efficiency of 12.2%, which will be fully characterized at the end of this last chapter through a combination of suitable experimental techniques, in order to highlight the factors which contributed to this huge jump in the power conversion efficiency. The stability in time of this optimized PV devices will finally be discussed.
2
Maslah, Zouhir. "Élastographie in vitro de cellules par opto-acoustique picoseconde : applications à la différenciation cellulaire." Electronic Thesis or Diss., Bordeaux, 2023. http://www.theses.fr/2023BORD0464.
Анотація:
La mécanique cellulaire est impliquée dans de nombreux processus biologiques tels que l'adhésion, la migration ou la différenciation. Évaluer les propriétés mécaniques des éléments cellulaires est essentiel pour comprendre leur fonction dans ces processus et permet d'anticiper les perturbations en cas d'altérations pathologiques. Cependant, les techniques traditionnellement utilisées pour caractériser mécaniquement les cellules ne permettent pas d’éliminer les interactions entre les différents éléments cellulaires lors des mesures. L’acoustique picoseconde offre une nouvelle opportunité grâce à la génération et à la détection d’ondes acoustiques dont les fréquences peuvent atteindre le térahertz. Nous avons élaboré un protocole expérimental pour effectuer des mesures d’acoustique picoseconde sur des cellules vivantes immergées dans un milieu de culture. À l’aide d’une chambre d’imagerie, conçue pour la microscopie directe et inversée, et d’un transducteur opto-acoustique biocompatible, nous pouvons réaliser des mesures non invasives des propriétés mécaniques avec une résolution spatiale micrométrique. Nous avons ensuite étudié l'impact de la fixation sur la structure interne du noyau, à l'aide de la diffusion Brillouin résolue en temps. Cette étude démontre que la célérité acoustique dans le noyau augmente avec la fixation. Ces changements ne sont pas homogènes, mais affectent principalement les éléments du nucléoplasme présentant la fréquence Brillouin la plus faible. Nous avons également démontré l’importance de maintenir l’hydratation des cellules fixées pour éviter les modifications irréversibles provoquées par la déshydratation. En effet, les cellules réhydratées ne retrouvent pas les mêmes propriétés mécaniques que celles qu’elles avaient avant la déshydratation. Enfin, nous avons étudié, grâce à une analyse statistique sur un grand nombre de cellules souches mésenchymateuses et d’ostéoblastes, comment la structure interne du noyau évolue avec la différenciation. En comparant les cellules incubées pendant 24 heures avec celles ayant été incubées pendant 14 jours dans un milieu ostéogénique, nous avons observé que les cellules différenciées présentaient une concentration de chromatine plus élevée que les cellules non différenciées. Cette concentration se traduit par une augmentation de la fréquence Brillouin, qui est attribuée à un changement de la rigidité du noyauCell mechanics is involved in several biological processes such as adhesion, migration, or differentiation. Evaluating the mechanical properties of cellular elements is essential to understand their function in these processes and allows anticipating disruptions in case of pathological alterations. However, the techniques traditionally used to mechanically characterize cells do not allow eliminating interactions between different cellular elements during measurements. Picosecond acoustics offer a new opportunity thanks to the generation and detection of acoustic waves whose frequencies can reach the terahertz. We have developed an experimental protocol to perform picosecond acoustic measurements on living cells immersed in a culture medium. Using an imaging chamber, designed for direct and inverted microscopy, and a biocompatible opto-acoustic transducer, we can perform non-invasive measurements of mechanical properties with micrometric spatial resolution. We then studied the impact of fixation on the internal structure of the nucleus, using time-resolved Brillouin scattering. This study shows that the acoustic velocity in the nucleus increases with fixation. These changes are not homogeneous but mainly affect the elements of the nucleoplasm presenting the lowest Brillouin frequency. We also demonstrated the importance of maintaining hydration of fixed cells to avoid irreversible modifications caused by dehydration. Indeed, rehydrated cells do not recover the same mechanical properties as they had before dehydration. Finally, we studied, thanks to a statistical analysis on a large number of mesenchymal stem cells and osteoblasts, how the internal structure of the nucleus evolves with differentiation. By comparing cells incubated for 24 hours with those incubated for 14 days in an osteogenic medium, we observed that differentiated cells had a higher chromatin concentration than undifferentiated cells. This concentration results in an increase in Brillouin frequency, which is attributed to a change in nuclear rigidity
3
Murawski, Jan. "Time-Resolved Kelvin Probe Force Microscopy of Nanostructured Devices." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-224810.
Анотація:
Since its inception a quarter of a century ago, Kelvin probe force microscopy (KPFM) has enabled studying contact potential differences (CPDs) on the nanometre scale. However, current KPFM investigations are limited by the bandwidth of its constituent electronic loops to the millisecond regime. To overcome this limitation, pump-probe-driven Kelvin probe force microscopy (pp-KPFM) is introduced that exploits the non-linear electric interaction between tip and sample. The time resolution surpasses the electronic bandwidth and is limited by the length of the probe pulse. In this work, probe pulse lengths as small as 4.5 ns have been realized.
These probe pulses can be synchronized to any kind of pump pulses. The first system investigated with pp-KPFM is an electrically-driven organic field-effect transistor (OFET). Here, charge carrier propagation in the OFET channel upon switching the drain-source voltage is directly observed and compared to simulations based on a transmission line model. Varying the charge carrier density reveals the impeding influence of Schottky barriers on the maximum switching frequency.
The second system is an optically-modulated silicon homojunction. Here, the speed of surface photovoltage (SPV) build-up is accessed and compared to timeaveraged results. Due to slow trap states, the time-averaged method is found to lack comprehensiveness. In contrast, pp-KPFM exposes two intensity-dependent recombination times on the same timescale — high-level Shockley-Read-Hall recombination in the bulk and heat-dominated recombination in the surface layer — and a delay of the SPV decay with rising frequency, which is attributed to charge carrier retention at nanocrystals.
The third system is a DCV5T-Me:C60 bulk heterojunction. The SPV dynamics is probed and compared to measurements via open-circuit corrected transient charge carrier extraction by linearly increasing voltage. Both methods reveal an exponential onset of the band bending reduction that is attributed to the charge carrier diffusion time in DCV5T-Me, and a double exponential decay, hinting at different recombination paths in the studied organic solar cell.
The above-mentioned experiments demonstrate that pp-KPFM surpasses conventional KPFM when it comes to extracting dynamic device parameters such as charge carrier retention and recombination times, and prove that pp-KPFM is a versatile and reliable tool for studying electrodynamics on nanosurfaces.
4
Smith, Nathanael Joseph. "Pump-probe and variable stripe length measurements on waveguides containing silicon nanocrystals." Phd thesis, 2005. http://hdl.handle.net/1885/151504.
5
Murawski, Jan. "Time-Resolved Kelvin Probe Force Microscopy of Nanostructured Devices." Doctoral thesis, 2016. https://tud.qucosa.de/id/qucosa%3A30326.
Анотація:
Since its inception a quarter of a century ago, Kelvin probe force microscopy (KPFM) has enabled studying contact potential differences (CPDs) on the nanometre scale. However, current KPFM investigations are limited by the bandwidth of its constituent electronic loops to the millisecond regime. To overcome this limitation, pump-probe-driven Kelvin probe force microscopy (pp-KPFM) is introduced that exploits the non-linear electric interaction between tip and sample. The time resolution surpasses the electronic bandwidth and is limited by the length of the probe pulse. In this work, probe pulse lengths as small as 4.5 ns have been realized.
These probe pulses can be synchronized to any kind of pump pulses. The first system investigated with pp-KPFM is an electrically-driven organic field-effect transistor (OFET). Here, charge carrier propagation in the OFET channel upon switching the drain-source voltage is directly observed and compared to simulations based on a transmission line model. Varying the charge carrier density reveals the impeding influence of Schottky barriers on the maximum switching frequency.
The second system is an optically-modulated silicon homojunction. Here, the speed of surface photovoltage (SPV) build-up is accessed and compared to timeaveraged results. Due to slow trap states, the time-averaged method is found to lack comprehensiveness. In contrast, pp-KPFM exposes two intensity-dependent recombination times on the same timescale — high-level Shockley-Read-Hall recombination in the bulk and heat-dominated recombination in the surface layer — and a delay of the SPV decay with rising frequency, which is attributed to charge carrier retention at nanocrystals.
The third system is a DCV5T-Me:C60 bulk heterojunction. The SPV dynamics is probed and compared to measurements via open-circuit corrected transient charge carrier extraction by linearly increasing voltage. Both methods reveal an exponential onset of the band bending reduction that is attributed to the charge carrier diffusion time in DCV5T-Me, and a double exponential decay, hinting at different recombination paths in the studied organic solar cell.
The above-mentioned experiments demonstrate that pp-KPFM surpasses conventional KPFM when it comes to extracting dynamic device parameters such as charge carrier retention and recombination times, and prove that pp-KPFM is a versatile and reliable tool for studying electrodynamics on nanosurfaces.
Книги з теми "Pump-Probe device":
1
Kavokin, Alexey V., Jeremy J. Baumberg, Guillaume Malpuech, and Fabrice P. Laussy. Strong coupling: resonant effects. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198782995.003.0007.
Анотація:
This chapter presents experimental studies performed on planar semiconductor microcavities in the strong-coupling regime. The first section reviews linear experiments performed in the 1990s that evidence the linear optical properties of cavity exciton-polaritons. The chapter is then focused on experimental and theoretical studies of resonantly excited microcavity emission. We mainly describe experimental configuations in which stimulated scattering was observed due to formation of a dynamical condensate of polaritons. Pump-probe and cw experiments are described in addition. Dressing of the polariton dispersion and bistability of the polariton system due to inter-condensate interactions are discussed. The semiclassical and the quantum theories of these effects are presented and their results analysed. The potential for realization of devices is also discussed.
Частини книг з теми "Pump-Probe device":
1
Lynch, Bryan E. "The ReliantHeart aVAD©." In Mechanical Circulatory Support, 103–9. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780190909291.003.0015.
Анотація:
The ReliantHeart aVAD© is a new intraventricular axial flow pump with pumping components that fit within the inflow cannula of the ventricular assist device (VAD). The aVAD© is an improvement over its predecessor, the extra-ventricular HeartAssist5 (HA5)™. The pumping components, inflow guide vane, impeller, and diffuser of the aVAD© are identical to those in the HA5, which in turn were derived from the original collaboration between Baylor College of Medicine and NASA. The current device provides excellent physiologic support for patients in end-stage heart failure and provides advanced ultrasonic flow measurements and performance data for wireless remote monitoring. In 2011 and 2012, the aVAD© was used successfully in calf studies as an artificial heart, with each ventricle being replaced by a modified HA5 VAD©. The two predecessor aVADs© were placed vertically, side by side, which provided a more compact total artificial heart with formable outflow graft protectors directed to the aorta and pulmonary artery. An ultrasonic flow probe accurately measures flow under all conditions, even in implants in place for years. The probe indicates flow in the range of –4 to +10 L/min with >95% accuracy. The probe can determine the relative contributions of the LVAD and native heart to adequate blood flow. The aVAD© meets the safety standards of the European Union and is sold in Europe. The aVAD is not yet available in the United States but is being tested under an FDA investigational device exemption.
2
Borrelli, S., S. T. Kempers, P. H. A. Mutsaers, and O. J. Luiten. "RF Cavity-based Ultrafast Transmission Electron Microscopy." In Structural Dynamics with X-ray and Electron Scattering, 557–88. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781837671564-00557.
Анотація:
Ultrafast electron microscopy is among the most significant inventions of the 21st century, enabling an understanding of structural dynamics on atomic spatial and temporal scales. With this perspective in mind, the chapter first provides an overview of the state-of-the-art ultrafast electron microscopy field. Afterwards, the development of the first RF cavity-based ultrafast transmission electron microscope at the Eindhoven University of Technology is discussed. This device provides ∼100 femtosecond temporal resolution and an extremely high repetition rate (3 GHz or 75 MHz) while preserving the atomic spatial resolution and the high electron beam quality of a conventional transmission electron microscope, and avoiding the need for a powerful photoemission laser. The chapter presents the working principle and design of the Eindhoven ultrafast microscope along with the unique applications that have emerged from this method, ranging from high-repetition-rate pump–probe experiments and radiation damage suppression to coherent manipulation of electron pulses with light.
Тези доповідей конференцій з теми "Pump-Probe device":
1
Dirisaglik, Faruk, Gokhan Bakan, Sadid Muneer, Nicholas Williams, Mustafa Akbulut, Helena Silva, and Ali Gokirmak. "Electrical pump-probe characterization technique for phase change materials." In 2016 74th Annual Device Research Conference (DRC). IEEE, 2016. http://dx.doi.org/10.1109/drc.2016.7548508.
2
Shimamura, Mitsuaki, Yutaka Togasawa, Hisashi Hozumi, Naruhiko Mukai, and Yasuhiro Yuguchi. "Development of Remotely Operated Inspection Devices for BWR Internals." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30033.
Анотація:
Two ultrasonic testing (UT) devices to inspect the internals of nuclear reactor have been developed. The one is a jet pump UT device to inspect the inner weld line of the jet pump, and the other is a shroud UT device to inspect the outer weld line of the shroud. The jet pump UT device is mainly composed of an inspection probe scanner and a wheeled platform with a telescopic guide. Since the inspection probe scanner has been designed slim enough to pass through the narrow opening of the jet pump nozzle, it can be remotely positioned inside the jet pump transported by the wheeled platform. The shroud UT device is mainly composed of a flat-type remotely operated vehicle (ROV) and a positioning mast of ROV. The ROV is installed remotely on the outer surface of the shroud using the positioning mast. And the ROV has been designed thin enough to pass through the narrow gap between the jet pump and the shroud, so that it can move horizontally on the surface of the shroud with automatic cable feeding. Consequently, the proposed remote and automatic inspection devices can perform the inspection work in short time without using fuel handling machine (FHM). Therefore, the inspections can be performed simultaneously with the refueling work, which contributes to the shortening of regular inspection periods of nuclear power plants.
3
Gontijo, I., D. T. Neilson, A. C. Walker, G. T. Kennedy, and W. Sibbett. "Nonlinear single wavelength polarisation switching in InP-based waveguides." In Nonlinear Guided Waves and Their Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/nlgw.1995.nsac1.
Анотація:
All-optical switches have attracted much attention due to their potential application in high speed optical communication systems. Among the many concepts that have been studied are pump/probe nonlinear etalon devices, both in InGaAs/InP1 in the wavelength range of 1.5μm and in GaAs-based structures2at 0.85μm. In general, the excite (pump) and probe wavelengths have to be different, to avoid probe absorption. The use of a single wavelength but different states of polarisation in the pump and probe beams to produce switching has been investigated in CdS.3 In this case, the device relies on the natural dichroism of a CdS crystal platelet, to absorb only light of a specific polarisation, which is chosen to be the pump. InGaAs/InP quantum wells exhibit much larger dichroism for TE/TM polarisations and we have observed large refractive index changes at wavelengths away from the bandedge.4 Reported below are experiments where a single wavelength was used, together with the large splitting between the heavy and light hole absorption bandedges in InGaAs/InP quantum well waveguides, to demonstrate a two- polarisation switch with signal gain. The waveguide, with uncoated facets, is a nonlinear Fabry-Perot etalon, whose refractive index can be changed by the absorption of the pump beam which in turn changes the cavity transmission characteristics sensed by the probe beam. This type of device could have important applications, as it uses a single wavelength and offers cascadability and compatibility of all-optical switching with optical fibre communications.
4
Klopf, J. Michael, John L. Hostetler, and Pamela M. Norris. "Transient Reflectance Response to Hot Electron Relaxation in InP Based Films." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39625.
Анотація:
Advancements in technologies related to thin film growth have led to astoundingly complex integrated photonic devices. The reliability of these devices relies upon the precise control of the band gap and absorption mechanisms in the thin film structures. Photon absorption in these devices can result in a reduction of laser efficiency as well as thermal runaway. To improve device performance prediction, an increased understanding of the localized absorption processes is paramount. A pump-probe technique is being developed to measure the transient absorption during hot carrier relaxation. This method relies upon the generation of hot carriers by the absorption of an intense ultrashort laser pulse. The change in reflectance due to hot carrier generation and relaxation is monitored using a probe pulse focused at the center of the excited region. The transient reflectance is measured as a function of the relative delay between the pump and probe pulses. Utilizing ultrashort laser pulses (τp ∼ 190 fs) it is possible to attain sub-picosecond resolution of the transient reflectance during hot carrier relaxation. Transient changes in the reflectance can then be related to transient changes in the absorption mechanisms of the film. Preliminary measurements made with this technique have shown clear differences in the transient reflectance of doped and undoped Indium Phosphide (InP) based films. This study will form the basis for development of a transient thermoreflectance model during hot carrier relaxation in III-V semiconductors.
5
Hong, John H., and Tallis Y. Chang. "Frequency-agile rf notch filter using photorefractive two-beam coupling." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.thu2.
Анотація:
In modern signal processing environments the ability to excise certain frequencies from a given rf signal, known as notch filtering, is a useful function. Programmability of the notch frequencies is a crucial capability in many applications, which at the same time is difficult using conventional electronic methods. Hybrid electrooptical (EO) methods have been proposed and demonstrated where spatial light modulators are used in conjunction with an acoustooptic (AO) device to perform the desired function via Fourier optics. In this paper, we describe a new approach using photorefractive two-beam coupling with EO modulators. Two-beam coupling is a non-linear optical phenomenon where two coherent beams of light can exchange energy in a photorefractive medium.1 Our system uses a generalization of this effect for temporally modulated beams which has been theoretically characterized elsewhere.1 Our system uses a two-beam coupling apparatus in which one beam (the pump) is modulated with the received signal to be filtered and the other (the probe) is modulated with synthesized sinusoids at the notch frequencies. The modulation is performed with either AO or EO devices. The two-beam interaction causes those portions in the pump beam with the same frequency content as those present in the probe beam to become almost completely diverted into the probe beam direction so that the pump beam that emerges from the photorefractive crystal is nearly devoid of those temporal frequencies. This beam is then directed into a heterodyne detector apparatus to recover the notch filtered signal.
6
True, Emily M., and Leon Mccaughan. "Optical nonlinearity in thin films of amorphous arsenic sulfide." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tuii3.
Анотація:
Bulk chalcogenide glass semiconductors have been shown to exhibit a large, yet fast absorption nonlinearity.1 The greatly broadened absorption edge characteristic of these amorphous semiconductors offer the possibility for large dynamic optical nonlinearities over a much larger range of wavelengths than found in crystalline materials. In addition, amorphous semiconductors are attractive for optical device applications because they can be deposited easily on a variety of substrates. Thin films of amorphous arsenic sulfide, a chalcogenide glass semiconductor, have been deposited on quartz and silicon substrates by ion beam sputtering. This method of deposition produces films which are amorphous, smooth, and of excellent optical quality. Preliminary measurements using a cw pump-probe technique show that, unlike in crystalline materials, where bandfilling effects cause a decrease in absorption, the absorption increases with pump intensity over a broad range of probe wavelengths. As in the bulk,1 the mechanism responsible for this effect is believed to be a result of structural disorder. Intraband transitions of a type forbidden in crystalline materials cause an increase in absorption at low energies when conduction band tail states are filled by bandgap energy radiation. Quantitative measurements of the change in the absorption spectrum of these films as a function of pump intensity and pump wavelength are presented.
7
Traghella, Daniele, Alessandro Paoli, Sandro Barone, and Armando V. Razionale. "Multi-Sensor Reverse Engineering Technique for the Acquisition of Centrifugal Pump Impellers." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-47219.
Анотація:
The geometrical reconstruction of centrifugal pump impellers is a strategic activity for many manufacturing industries. In particular, the digitalization of internal hydraulic shapes represents the most critical task due to the difficulties in accessing the internal parts of impeller disks. In this paper, an automatic approach to digitize the internal shape of impellers is presented. The methodology is based on the integration of optical and probing methods in order to combine the advantages of both technologies. The developed approach uses an optically tracked hand-held probe designed to digitize, point-by-point, the whole surface of blades. The tracking system is based on a passive device, composed of two stereo cameras, which is used to accurately locate a specific plate, rigidly connected to a probe. The proposed methodology has been validated by experimental tests on primitive surfaces as plane, cylinders and spheres. Nonetheless, the robustness and flexibility of the developed technique has allowed the whole reconstruction of industrial impellers through the acquisition of hundreds of points in few minutes.
8
Jewell, J. L., Y. H. Lee, M. Warren, H. M. Gibbs, and N. Peyghambarian. "Low-Energy, Fast, Thermally-Stable Optical Nor Gate in a Room-Temperature GaAs Etalon." In Optical Computing. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/optcomp.1985.md1.
Анотація:
A simple pump-and-probe technique for using a dispersively nonlinear Fabry-Perot etalon as NOR, NAND, XOR. OR and AND gates has been previously described and demonstrated using dye-filled etalons.1 We have now performed these five logic functions in a room-temperature GaAs-AlGaAs multiple-quantum-well (MQW) etalon at 82 MHz with input energies less than 3 pJ incident on the device achieving contrasts better than 5:1. Thermal stability with respect to input data was demonstrated in the NOR rate despite poor heatsinking. A similar Fabry-Perot MQW device has shown 1-ps response time.2
9
Jones, Paul M., Joachim Ahner, Christopher L. Platt, Huan Tang, and Julius Hohlfeld. "Carbon Overcoat Loss From the Surface of a Heat Assisted Magnetic Storage Disk due to Laser Irradiation." In ASME 2013 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/isps2013-2947.
Анотація:
A pump-probe experimental technique that incorporated a 527nm wavelength pump laser and a 476nm probe laser was applied to a magnetic storage disk having a magnetic layer comprised of a FePt alloy and coated with a hydrogenated carbon overcoat (COC). The pump laser power was systematically increased while sweeping the applied field with an electromagnet to observe the temperature dependent magnetization, which is proportional to the change in the polarization of the reflected beam. In this way the laser power required to heat the media to the Curie temperature (Tc) was determined, with the Curie temperature of the media determined from a separate magnetometry measurement. Such a single point laser power-to-media temperature calibration allowed the determination of the media temperature over a small laser power range near Tc. The carbon over-coated FePt media was then irradiated for varying durations at temperatures pertinent to a Heat Assisted Magnetic Recording (HAMR) device [1]. The COC surface topography and carbon bonding structure within each irradiated zone was probed with AFM and micro-spot Raman. A subtle, systematic temperature and duration dependent change in the COC was observed. With increasing temperature and duration, the Raman D-peak became increasingly pronounced, signaling an increase of the sp2 (disorder) content in the film in the irradiated region. At incrementally higher temperatures, the loss of the carbon overcoat becomes apparent as a shallow depression in the COC film in the irradiated area. A clearer picture of the possible sensitivity and kinetics of the loss of COC on the HAMR media surface was obtained by measuring its loss over a range of irradiation temperatures and durations. The activation energy and COC loss rate were obtained and a possible mechanism for COC failure-loss was discussed within the bounds of the operating HAMR device [2].
10
Christofferson, James, Kazuaki Yazawa, and Ali Shakouri. "Picosecond Transient Thermal Imaging Using a CCD Based Thermoreflectance System." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22969.
Анотація:
A new Charge Coupled Device (CCD) based, full-field thermoreflectance thermal imaging technique is demonstrated with 800 picoseconds temporal resolution. Transient thermal images of pulsed heating in single interconnect vias of 350nm and 550nm in diameter are shown. The use of pulsed laser diodes and dedicated synchronization circuits can significantly lower the cost and the image acquisition time compared to the scanning pump-probe laser systems. Also the same set up can be used to study transient thermal phenomena in a wide dynamic range from sub nanoseconds to seconds.