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Carrier and phonon dynamics in Bi2Se3 crystals are studied by a spatially resolved ultrafast pump-probe technique. Pronounced oscillations in differential reflection are observed with two distinct frequencies, and are attributed to coherent…

Mesoscale and Nanoscale Physics · Physics 2011-06-08 Nardeep Kumar , Brian A. Ruzicka , N. P. Butch , P. Syers , K. Kirshenbaum , J. Paglione , Hui Zhao

We study the relaxation of coherent acoustic phonon modes with frequencies up to 500 GHz in ultra-thin free-standing silicon membranes. Using an ultrafast pump-probe technique of asynchronous optical sampling, we observe that the decay time…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 J. Cuffe , O. Ristow , E. Chávez , A. Shchepetov , P-O. Chapuis , F. Alzina , M. Hettich , M. Prunnila , J. Ahopelto , T. Dekorsy , C. M. Sotomayor Torres

Spatiotemporal dynamics of electron-hole pairs locally excited in a silicon-on-insulator structure by indirect interband absorption are studied by measuring differential transmission caused by free-carrier absorption of a probe pulse tuned…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Hui Zhao

The ultrafast thermal and mechanical dynamics of a two-dimensional lattice of metallic nano-disks has been studied by near infrared pump-probe diffraction measurements, over a temporal range spanning from 100 fs to several nanoseconds. The…

Femtosecond optical pump-probe technique is used to study charge carrier dynamics in few-layer MoS2 samples fabricated by mechanical exfoliation. An ultrafast pump pulse excites carriers and differential reflection of a probe pulse tuned to…

Mesoscale and Nanoscale Physics · Physics 2011-11-01 Rui Wang , Brian A. Ruzicka , Nardeep Kumar , Matthew Z. Bellus , Hsin-Ying Chiu , Hui Zhao

We report on time-resolved optical and terahertz ultrafast spectroscopy of charge-carrier dynamics in the room-temperature antiferromagnetic semiconductor $\alpha $-MnTe. By optically pumping the system with 1.55 eV photons at room…

Ultrafast phenomena on a femtosecond timescale are commonly examined by pump-probe experiments. This implies multiple measurements where the sample under investigation is pumped with a short light pulse and then probed with a second pulse…

The small mass and high coherence of nanomechanical resonators render them the ultimate force probe, with applications ranging from biosensing and magnetic resonance force microscopy, to quantum optomechanics. A notorious challenge in these…

Quantum Physics · Physics 2017-07-18 Yeghishe Tsaturyan , Andreas Barg , Eugene S. Polzik , Albert Schliesser

Contemporary quantum plasmonics capture subtle corrections to the properties of plasmonic nano-objects in equilibrium. Here, we demonstrate nonequilibrium spill-out redistribution of the electronic density at the ultrafast time scale. As…

We demonstrate pump-probe techniques, namely the Doppler spectrometry and the reflectometry in detail, which directly capture the time-resolved ultrafast evolution of high intensity femtosecond laser-driven hot, dense plasma. These…

We employ few-femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy to reveal simultaneously the intra- and interband carrier relaxation and the light-induced structural dynamics in nanoscale thin films of layered…

Time-dependent femtosecond pump-probe spectroscopic ellipsometry studies on zincblende gallium-nitride (zb-GaN) are performed and analyzed between 2.9-3.7eV. An ultra-fast change of the absorption onset (3.23eV for zb-GaN) is observed by…

This study examines the Raman scattering and charge transfer properties of molecules adsorbed on the surface of a tetrahedral Au$_{120}$ nanoparticle based on the time-dependent density functional tight-binding (TD-DFTB) method. We study…

Chemical Physics · Physics 2024-09-18 Sajal Kumar Giri , George C. Schatz

Transient reflectivity spectroscopy is widely used to study ultrafast carrier- and phonon-dynamics in semiconductors. In their heterostructures, it is often not straightforward to distinguish contributions to the signal from the various…

Mesoscale and Nanoscale Physics · Physics 2022-02-09 Kunie Ishioka , Ethan Angerhoffer , Christopher J. Stanton , Gerson Mette , Kerstin Volz , Wolfgang Stolz , Ulrich Höfer

Nonlinear selective reflection from the interface YAG window-high density rubidium vapor in the high-temperature cell is studied at the transition 5S$_{1/2}$-5P$_{3/2}$. In the experiment tunable pump and probe lasers are used. The…

Atomic Physics · Physics 2024-07-10 V. A. Sautenkov , S. A. Saakyan , A. A. Bobrov , B. B. Zelener

We apply the coupled dynamics of time-dependent density functional theory and Maxwell equations to the interaction of intense laser pulses with crystalline silicon. As a function of electromagnetic field intensity, we see several regions in…

Other Condensed Matter · Physics 2015-06-03 K. Yabana , T. Sugiyama , Y. Shinohara , T. Otobe , G. F. Bertsch

We present a real-time investigation of ultrafast carrier dynamics in single-wall carbon nanotube bundles using femtosecond time-resolved photoelectron spectroscopy. The experiments allow to study the processes governing the subpicosecond…

Materials Science · Physics 2009-11-07 Tobias Hertel , Roman Fasel , Gunnar Moos

Ultrafast optical pump-probe spectroscopy is used to track carrier dynamics in the large magnetoresistance material WTe$_{2}$. Our experiments reveal a fast relaxation process occurring on a sub-picosecond time scale that is caused by…

Solution-processable two-dimensional (2D) semiconductors with chemically tunable thickness and associated tunable band gaps are highly promising materials for ultrathin optoelectronics. Here, the properties of free charge carriers and…

The nonlinear characteristics of hydrogenated amorphous silicon nanowires are experimentally demonstrated. A high nonlinear refractive index, n2=1.19 x 10-17 m2/W, combined with a low two-photon absorption, 0.14 x 10-11 m/W, resulted in a…