Optically Induced Sub-Wavelength Transient Apertures in Sb-Te Based Films

2011 ◽  
Vol 1338 ◽  
Author(s):  
Robert E. Simpson ◽  
Paul J. Fons ◽  
Alexander V. Kolobov ◽  
Xiomin Wang ◽  
Junji Tominaga
Keyword(s):  
Thin Films ◽  
Density Functional ◽  
Near Field ◽  
Diffraction Limit ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Thermally Induced ◽  
Melting Temperatures ◽  
Sub Wavelength

ABSTRACTThe origin of sub-diffraction-limit apertures in Sb-based thin films is discussed. Electromagnetic energy can be channeled by these apertures thus allowing near-field focussing- the Super-RENS effect. The aperture formation within Sb, Sb2Te3, Sb2Te, SbTe and Ge2Sb2Te5 is investigated by time resolved optical pump-probe techniques and found to occur without melting. Density functional calculations have shown that these materials exhibit a thresholdlike change in their optical properties below their melting temperatures. The threshold is shown to be a consequence of thermally induced misalignment of p-orbital bonds. It is the non-linearity of this process that leads to the formation of the sub-diffraction-limit apertures.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

scholarly journals Time-resolved x-ray/optical pump-probe simulations on N2 molecules

2019 ◽  
Vol 6 (2) ◽  
pp. 024101
Author(s):  
Athiya Mahmud Hanna ◽  
Oriol Vendrell ◽  
Robin Santra
Keyword(s):  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray

scholarly journals Unambiguous determination of spin dephasing times in ZnO by time-resolved magneto-optical pump-probe experiments

2014 ◽  
Vol 251 (9) ◽  
pp. 1861-1871 ◽  
Author(s):  
Sebastian Kuhlen ◽  
Ralph Ledesch ◽  
Robin de Winter ◽  
Matthias Althammer ◽  
Sebastian T. B. Gönnenwein ◽  
...  
Keyword(s):  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Spin Dephasing ◽  
Unambiguous Determination

Ion-beam milling of YBCO thin films and their characterization by time-resolved pump-probe method

1999 ◽  
Vol 9 (2) ◽  
pp. 1952-1955 ◽  
Author(s):  
M. Hangyo ◽  
S. Nashima ◽  
M. Kawamura ◽  
S. Shikii ◽  
M. Tonouchi
Keyword(s):  
Thin Films ◽  
Ion Beam ◽  
Probe Method ◽  
Time Resolved ◽  
Pump Probe ◽  
Ybco Thin Films

Plasmonic Lithography

2004 ◽  
Author(s):  
W. Srituravanich ◽  
N. Fang ◽  
C. Sun ◽  
S. Durant ◽  
M. Ambati ◽  
...  
Keyword(s):  
Surface Plasmons ◽  
Ion Beam ◽  
Near Field ◽  
Diffraction Limit ◽  
Fdtd Simulation ◽  
Hole Array ◽  
Exposure Test ◽  
Spacer Layer ◽  
Bull's Eye ◽  
Sub Wavelength

As the next-generation technology moves below 100 nm mark, the need arises for a capability of manipulation and positioning of light on the scale of tens of nanometers. Plasmonic optics opens the door to operate beyond the diffraction limit by placing a sub-wavelength aperture in an opaque metal sheet. Recent experimental works [1] demonstrated that a giant transmission efficiency (>15%) can be achieved by exciting the surface plasmons with artificially displaced arrays of sub-wavelength holes. Moreover the effectively short modal wavelength of surface plasmons opens up the possibility to overcome the diffraction limit in the near-field lithography. This shows promise in a revolutionary high throughput and high density optical lithography. In this paper, we demonstrate the feasibility of near-field nanolithography by exciting surface plasmon on nanostructures perforated on metal film. Plasmonic masks of hole arrays and “bull’s eye” structures (single hole surrounded by concentric ring grating) [2] are fabricated using Focused Ion Beam (FIB). A special index matching spacer layer is then deposited onto the masks to ensure high transmissivity. Consequently, an I-line negative photoresist is spun on the top of spacer layer in order to obtain the exposure results. A FDTD simulation study has been conducted to predict the near field profile [3] of the designed plasmonic masks. Our preliminary exposure test using these hole-array masks demonstrated 170 nm period dot array patterns, well beyond the resolution limit of conventional lithography using near-UV wavelength. Furthermore, the exposure result obtained from the bull’s eye structures indicated the characteristics of periodicity and polarization dependence, which confirmed the contribution of surface plasmons.

scholarly journals Pump-Probe Time-Resolved Serial Femtosecond Crystallography at SACLA: Current Status and Data Collection Strategies

2019 ◽  
Vol 9 (24) ◽  
pp. 5505 ◽  
Author(s):  
Eriko Nango ◽  
Minoru Kubo ◽  
Kensuke Tono ◽  
So Iwata
Keyword(s):  
Data Collection ◽  
Free Electron ◽  
Free Electron Laser ◽  
Current Status ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray ◽  
Collection Strategies ◽  
Serial Femtosecond Crystallography

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.

scholarly journals Using computational chemistry to design pump-probe schemes for measuring radical cation dynamics

2021 ◽  
Author(s):  
Hugo López Peña ◽  
Derrick Ampadu Boateng ◽  
Shane McPherson ◽  
Katharine Moore Tibbetts
Keyword(s):  
Potential Energy Surfaces ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Excitation Wavelength ◽  
Functional Theory ◽  
Time Resolved ◽  
Pump Probe ◽  
Energy Surfaces ◽  
Electronic Potential

The electronic potential energy surfaces of nitrobenzene cation obtained from time-dependent density functional theory calculations are used to predict the most efficient excitation wavelength for femtosecond time-resolved mass spectrometry measurements....

Thermal Isomerization of [Co(acac)2(N3)(py)] in Liquid Solution Studied by Time-Resolved Fourier-Transform Infrared Spectroscopy

2020 ◽  
Vol 234 (7-9) ◽  
pp. 1549-1566 ◽  
Author(s):  
Tobias Unruh ◽  
Peter Vöhringer
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Rate Constants ◽  
Density Functional ◽  
Fourier Transform Infrared ◽  
Liquid Solution ◽  
Time Resolved ◽  
Thermally Induced ◽  
The Individual

AbstractThe thermally induced stereochemical interconversion between the trans and cis isomers of [Co(acac)2(N3)(py)] in liquid solution is investigated with time-resolved Fourier-transform infrared spectroscopy. The complex is synthesized stereo-selectively in its trans-form. Upon dissolution of the trans-form, the kinetic build-up of the cis-form is evidenced by the spectro-temporal evolution of the FTIR-spectrum. The individual isomer-specific component spectra are in good agreement with calculated spectra obtained from density functional theory. The rate constants of the forward and backward reactions responsible for the trans-cis isomerization equilibrium are derived from the kinetic traces in combination with existing thermochemical data from the literature. Moreover, the temperature-dependence of the rate constants are in line with Arrhenius activation energies of (122 ± 8) kJ/mol and (109 ± 8) kJ/mol for the forward and backward reactions, respectively. DFT-calculations suggest that the stereochemical rearrangement is caused by a pyridine rebound mechanism involving penta-coordinated square-pyramidal [Co(acac)2(N3)]-intermediates.

Photoelectrical Parameters of a PVT Grown Bulk 15R-SiC Crystal at Different Stages of Growth

2015 ◽  
Vol 821-823 ◽  
pp. 253-256
Author(s):  
Gediminas Liaugaudas ◽  
Donatas Dargis ◽  
Kęstutis Jarašiūnas ◽  
Nikolaos Tsavdaris ◽  
Eirini Sarigiannidou ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Crystal Growth ◽  
Room Temperature ◽  
Vapour Transport ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Trap Concentration ◽  
Stages Of Growth

The electronic quality of a Physical Vapour Transport (PVT) grown 15R-SiC crystal at different stages of growth was assessed by time-resolved optical pump-probe techniques. The measured differential transmittivity (DT) kinetics for the layers corresponding to the initial, middle and final stages of growth revealed clear differences in the decay of the DT signal, indicating a decreasing concentration of traps at the later stages of the crystal growth. The estimated trap concentration in the initial layer wasNT≈ 1019cm-3, while it decreased down to less than 2×1018cm-3in the top layer. The injection dependence of the diffusion coefficient at room temperature confirmed the gradual decrease ofNTin the layers corresponding to later stages of growth. Accordingly, the bipolar diffusion coefficient in the middle and the top layer wasDa≈ 2 cm2/s, whileDa= 0.9 cm2/s was measured in the layer closest to the seed.

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